Just interested want do ya'll think was more driving influence from mostly mail to mostly plate for the most well off in the 14th century. Did the development of more powerful, larger, more precise weapons spur the development armor, or did the development of better armor drove the development of more percise, or larger, more powerful weapons?

Certain advancements in metallurgy and, probably even more importantly, centralization of industry and economy. Plate simply became cost effective.

There is some support for the idea that the armour did precede changes in arms from manuscript evidence. It's not until quite late, post 1370 AD if I recall correctly, that swords are mostly represented with thin points consistent with Type XV, XVa and XVII swords. Assuming this is accurate to reality, that means that a surprising number of warriors were still using Type XII and Type XVI family blades in the 1350's and 60's.

Likewise, there is evidence for early forms of coats-of-plates prior to any confirmed examples of Type XV swords, XIVs, and XVIs. Although mail seems to have predominated throughout the century, transitions in armour seemed to have preceded transformations in swords. However, it is worth notimg that swords with points acute enough to pierce the articulations of full plate, the XV family, predate full plate.

No sword can punch through plate. It doesn't matter what kind of point or geometry it has. The new sword types must have been developed for some other reason. If they were designed to punch through the gaps in plate then they were really designed to punch through mail. If this is the case then why were they not developed when mail covered all of the body?

I must agree with Mikko to a point. Advances in metallurgy drastically lowered the cost of sheet iron and alloys. However to argue this change alone ignores significant changes in labour cost associated with the Black Death wiping out huge swathes of the population. More importantly, this line of argument - technological determinism - is deeply flawed in the study of 14thC European history.

The very nature of warfare began to change in the early 14thC, from cavalry accustomed to the safety of presumed ransom if captured to absolute slaughter by base infantry. (see Kelly DeVries numerous books and papers) Military professionalism also accounts for some of the rapid changes in demand for more complete but manageable improvements in protection. These are social constructs.

The concept of a medieval "arms race" is fairly dated by today's state of historical research, as well as being somewhat anachronistic.

Isn't this covered in the Mail Unchained article. I've seen some criticism of the article but there hasn't been any criticism of that part.

Sorry back at you Kel. It wasn't directed at you but rather it was a general response to the OP. The last section is called "Plate Development" and answers the OPs question. To summarise, as you said, it was a combination of technological and social developments.

I have limited knowledge in this and am likely wrong. But while I believe few historical changes can be boiled down to single factors, if I had to say 'this is why' I would say cost. It is my understanding that advances in metallurgy and metal working eventually led to plate being less costly in both time and money to produce than chainmail. From the little practical experiments I've seen or heard about it doesn't appear that plate really offered significantly more protection over chainmail... Which really surprised me.

The Wisby battlefield has been discussed here before. We have dozens and dozens of wounds on many bodies yet there isn't a single one on the torso. Either body armour was invulnerable to the weapons of the time or people simply didn't attack the torso because of the presence of armour. IMO it was a bit of both.

Well, two things, soft tissue damage like being speared in the gut wouldn't show up on remains. Secondly, Any decent sized shield does a damn good at protecting your torso so even if your where not armored in the torso, so there is an incentive to aim for the neck, limbs, arms and head even if you are lacking decent torso armour.

How lethal are gut wounds anyways? Outside of getting hit in a major blood vessel or getting something like your liver punctured there doesn't seem to be an awful lot there that would instantly render you dead or incapacitated. A lot of people get stabbed in the gut in modern knife attacks don't they?

And any puncture of the intestines goes septic very quickly and the dying is slow and painful