Handling, function and performance in a sword depends on many factors.
Very few of these factors act independently.

Vibration nodes and their placing have an effect on stiffness and vibration dampening.

Placing of pivot points is an effect of the dynamic balance of a sword (the way the sword behaves while in motion). The pivot points also play a role in shock dampening.

Normally when you take measurements on a sword you use the guard (or the shoulders of the blade) as 0: it is a good and handy neutral.

Terms like pivot points and vibration nodes (or even harmonc balance or dynamic balance) can be helpful in that they define some certain aspects of the functional properties of a sword. Unfortuantely, they can also be used in a way that is misleading and confusing when not applied correctly or too broadly. Having defined aspecs might make it seem that we have all the important facts laid out before us. If we only put the correct data in these specific values, we get a superior sword...

In reality, swords are complex. No single statistic or limited set of statistics will really tell you all you need to know to get a complete picture.
You can get some kind of impression however, and that is why makers provide a basic set of stats for customers to get a general idea of the characteristics. Personally I think a short description of type and character (without numbers and measurements) is more valuable. When you read Oakeshotts work you see how he excells at this: he manages to describe swords types and their development with very littel numenrical information. I think he was well aware that many of the important things are not really measurable.
When documenting swords I note physical dimensions such as lengths, widths and thicknesses of different parts, shapes of cross sections and volumes, mass and point of balance, placing of vibration nodes in grip and blade and correlation between pivot points in grip and blade. These are the most important points of reference. *Together* they provide a "profile" or functional ID of a sword. They act as a reference to the memory of the feel of the sword together with drawings and photos. No stat or detail alone will tell you much. It is all in the combination of features and characteristics: the proportion, ratio and relation between the spesifics.
Still I value most a personal impression of a weapon. I will never attempt to make a true copy or reconstruction of a sword if I have not held it in my own hands and spent some time with it. A list of numbers can never replace that.

The fact that you can measure certain aspects of a sword is helpful. Still, it is what is *between and behind* those numbers that really matters.

This topic has been promoted into a Spotlight Topic.

Since this thread has varied a great deal from the original topic, I thought I'd add more to this.........

We've kind of concentrated on the blade, which is easy to do, because its the most important part of the sword. But the ergonamic parts of the blade are important too..... How the operator of the sword's hand works with the handle, relates to guard and pommel will be a part of the handling and striking equation. How a hand interacts with the grip can make or break the relationship of sword and swordsman.........

Also, back to the blade.......... everything is interconnected. You cannot over concentrate on the pivot points, as moving them will effect the nodes. Over doing the handle nodes, for instance, can and will effect the pivot points......Etc and so on.

After a while, things become just as subjective for maker as for the swordsman. Most sword handlers just want the sword to do the things they think a sword should. They want it to handle well, cut well etc....... If they are studying a certain art, Fiore longsword for instance, they want the sword to complement what they're doing.......... If the sword does that, and does it well, alls well with the swordsman's world........

A swordmaker eventually can "feel" whether a sword is "there" harmonically and dynamically, by just doing a few drills. Don't really need to slap the blade anymore, or measure pivot points. Does the sword track right? Does it follow the point naturally in a curving thrust? Or does it over or under steer? How does it react to the swordsman's footwork and technique?

Then we have to deal with the sword's design criteria and intended function. There was a lot of diversity during the medieval period, and a fifteenth century longsword intended for unarmored longsword work is going to be much difference in appearance, handling, function than an early 14th century warsword.............

As westerners, we quite often over analyze things, and miss the whole....... Does the sword do what it should? Or doesn't it?

Things like cop are important, but two different people can measure the same sword, and come up with a different measurement, by as much as three inches on a 35 inch blade........ So, most experienced people don't concern themselves so much with dry statistics..... what does the sword actually do?

The review of the Albion Landgraf and Sempach might reinforce your very accurate point Angus.
http://www.myArmoury.com/review_alb_lansem.html

Changes in grips (riser, shape, etc.) or pommels and guards have a signficant influence on the human factors that affect our perceptions of handlng even when the blade is the same blade. It is intriguing to see to models with very close statistics and the same blade design receieve recognition of very different handling traits / preferrences in a review like that.

To me this topic has gotten way "over complicated". While the dynamics and engineering of sword blades is interesting, I liken it to a car. Many of today's modern cars are engineering marvels and I appreciate the work that goes into it and how all the pieces are integrated. However, as long as it performs the way I need it to, all that is relatively unimportant. If I buy a Type XII sword I know I am getting what is primarily a cutter adn I shold know about where I would get optimum cuts on that blade type. Thus would talk to whomever the manufacturer is and ask them where that "sweet spot" lies. If I decide to buy the sword, then when it arrives I can give the blade a whack and reasonably know where that first node is on the blade. No need to realy on a quantified definition of what the COP is. As Gus stated, the COP (whatever that is) is not the only thing that makes a great sword. I haev seen swords where the COP is in the proper place ( for its type) and th thing literally jumps out of your hand when you strike from vibrations to the handle. So this thread in a way frustrates me as well as fascinates me. People like Gus, Albion, Peter J and others survive in this niche business because they consistantly turn out quality products that react as we expect ( sometimes beyond what we expect ).

While I believe that an engineering paper on the mechanical and dynamic properties of a sword would be extremely interesting ( and probably overdue), all we seem to be doing here is covering the same ground with teh same questions. I am not trying to be negative, but there are far more aspects to sword design than COP and all of them are probably so interrelated that you cannot discuss one without the others.

To answer Vincent's question about big two-handers, it is possible to get the balde to wobble when moving from guard to guard. To be honest, this doesn't affect you all that much when the blade is properly balanced. I cannot say what sparring is like with one of these blades when you start parrying with another sword; something I have not done. I do know that to get good cuts and edge alignment you have to be precise with your technique. However, I would venture to say that even a misaligned cut with a blade of this size would be traumaticfor your opponent!

Joel Whitmore

Aspects of sword handling are very complicated. Believe it or not, so is the way a golf ball behaves when struck. In the context of sword reviews “CoP” seems to convey a much more complicated and integrated set of performance aspects of swords than the simple physics definition of Center of Percussion (CoP.)

There are some personal interpretations I have gained more confidence in from this post with respect to typical broad swords.

• The location typically described as “CoP” in sword reviews is an “approximately optimum” place for a sword edge to make contact when striking as if the reviewers intended to cut. It is analogous to the term “sweet spot” often used when technical industries discuss some types of athletic equipment. The pivot point corresponding to this “CoP” might occur at some non intuitive locations (such as completely beyond the sword pommel, out in the air somewhere…)
• The better manufacturer’s and reviewers are doing their best to identify this optimum impact location based on experience and actual trial usage which factors in “ergonomic aspects” and all of the complex interactions from grip, pommel, guard, etc. It is not just arbitrarily calculated based on some assumed pivot point and the mass distribution of the sword.
• It has been asserted that for swords “CoP” is universally specified in terms of a distance out in front of the guard, even if not every one states this. This might be the most useful aspect of the statistic (have not quite made up my mind) since it indicates about how far from an opponent the wielder should probably be when striking to cut.
• With good design practices resulting vibrations and harmonics are tuned to be dampened in the grip area and blade “CoP” area when impacts occur near this “CoP.” Sword strength/ durability should also accommodate impacts at this CoP location. However, these complex aspects of the design are not guaranteed to be optimized at the “CoP” for every sword you might come across. I personally value these aspects of the design greatly, but would exclude them from definitions of CoP.

Angus,

I'm quite with you on the ergonomy issue. That's a completely different problem, having almost nothing to do, I believe, with the physics of handling, and all to do with the shape and materials of the handle, even heavily dependant on the particular physionomy of your hand... Not something I would try to put into numbers, for sure. It has to be experienced first-hand, even a review is not terribly helpful here since your tastes and morphology can significantly differ from those of the reviewer.

On the review of the two Albion swords cited by Jared, I'd like to point out that though the blade is the same, the change of grip does not just have an effect on ergonomy, it also affects the balance. According to the review, the location of the POB was shifted by 3/4in, which I consider big enough. Indeed the effect on pivot points must be even greater, and that could explain to some extent the variation in handling.

I agree with you and Joel as well about the fact that appreciating a sword when in your hand does not have to rely on statistics either. When you are experienced enough with the kind of sword you are interested in, you don't need statistics, as long as you can lay your hands on the weapon. And indeed it is very simple, that's what I felt several times as well.

However, the weapon is not always at hand, and there are virtues I can see in calculating numerical properties.

It allows to remotely appreciate a sword, at least, some properties of it, which is better than nothing. It's complimentary to a reviewer's opinion in this respect, since you can directly compare it to things you know, whereas a reviewer probably has had different experiences than yours. It allows you, in a way, to confirm and weight the opinion of the reviewer. Imagine what someone proficient only in sport fencing would write about a type XI sword, even one very well done. He could be saying in his review that the balance is horrible... But if you are able to compare numerical figures with others you know, you can adjust the appreciation of the balance and conclude that after all this seems right. It does not invalidate the review, which still could contain useful information about materials, assembly, decoration, whatever... The numbers give you a reference point. OK, that's a rather extreme example, but I hope you get my point here. Something similar probably does happen in real life, to a more limited extent.

Numbers act as common references, allowing comparison without physical contacts. Comparing swords in museums comes to mind in this respect. Having some carefully chosen, representative numbers could prove immensely useful to an inexperienced newcomer, in my opinion. Now, the question of what those numbers should be is truly difficult... A question I will not try to answer here, since it's way off-topic and would necessitate a detailed explanation.

The starting point of the thread was the relative uncertainty about the definition of the COP. I don't think that it's a good idea to consider that there are many elements, subjective such as comfort, mixed in a number. In the end it amounts to say that somehow we are giving a "grade", and not measuring something. In that case I would trust more the ability of the reviewer to express his opinion in words, with nuance and compromises, rather than a mono-dimensionnal number that cannot reflect the various trade-offs that have to be made to obtain a good sword. But then that's just my point of view as a sword buyer/user...

Well, informative discussion anyway. I hope those matters will continue to be discussed in the future...

Regards