So I've seen plenty of books on Historical Long-sword fighting, but I have yet to see one that focuses on sword and shield. (buckler not included). I am interested in techniques that might have been used with a kite shield or a heater.

Any good books out there?

First, what do you mean by books? Ancient fencing treatises or modern interpretations of them?

Second, the grip style is more significant than the shield size or shape. Broadly speaking there's two grip styles to be concerned with, center gripped like a "Viking" shield and most bucklers or enarmes like most "heater" or "kite" shields. Certain sizes and shapes of shield allow you do perform actions in particular ways but that's secondary to grip style and shields were commonly scaled up or down. For instance there is historical artwork of "heater" shaped bucklers and even the strangely shaped bucklers shown in Talhoffer have full-sized counterparts. The pavise can be a shield that stands up all on its own and you hide behind or it can a small shield/large buckler you hold in one hand.

KDF seems to have evolved from a center-gripped shield and sword style so you can look in those sources for that kind of material. The rotella uses enarmes and is taught in the Bolognese material. While specific grip arrangements were more typical of certain shield shapes you can find both major styles on most major shield shapes throughout most of history, sometimes even in the same society.

Roberto,

There are no fencing books that teach the use of sword and heater shield. However, the good news is that there are a lot of primary source images from various manuscripts showing knights and men-at-arms using sword and heater. This means that it is possible to reconstruct sword and heater by studying these images.

A good place to start is http://manuscriptminiatures.com. I would do a search from the year 1200 AD to 1320 AD, which will give you hundreds of images to look through. Then, copy and save various images you want to refer to later.

From what I understand of sword and shield fighting, the shield's primary purpose is to bind the sword leaving you free to strike to another target. By contrast, with a long sword, the sword itself is the only means of binding. Of course, you can still bind sword-to-sword when fighting with heater shields; typically, though, after the swords bind it makes sense to displace the opponent's sword with your shield and strike to the next opening.

When it comes to using the heater shield, it seems that the two main motions you make (assuming you are right handed and have your shield on your left arm) are turning your shield outward (to your left) to close-off the line of attack and bind the sword, or turning the shield inward (to your right) to displace and deflect attacks.

Some people advocate exclusively turning the edge of the shield towards your opponent and only using the edge to displace—in other words, you receive every strike or thrust with the edge. I disagree with this idea of exclusively using the edge. There's nothing wrong with turning your edge towards your opponent to displace his attack, if you so choose, but it's not the only way to use a shield. When you turn your shield inward and outward and use it to bind as I described, you can keep your opponent from being able to effectively attack you for a moment or two while you land your blow. The other reason that always turning the edge forward does not make sense is that battles are not one-on-one duels. If you are mostly holding your shield with the edge turned forward, you are unnecessarily exposing yourself to arrows, bolts, javelins, and the like.

In my view, the reason this “always displace with the edge” belief arouse was that people looked at primary source images of knights fighting with sword and heater shield, and seeing an image which probably depicted the knight turning his shield edge outward to cover against a blow assumed that the knight was using the edge itself to receive all attacks. Again, there's nothing wrong with turning the shield so that the edge is forward and using that edge to displace a blow; it's certainly martially valid. It's just the idea that this is the only “proper way” to fight with sword and heater shield is a bit silly. It also makes a lot of sense to use the face of the shield, turning it inward or outward to close the line of attack, and bind the opponent's sword.

Of course, there are other things you can do with a shield too, like using it to immobilize an opponent's shield or even striking with the shield, but rather than listen to me, I recommend you study the images from Manuscript Miniatures themselves.

PS: Roland Warzecha of Dimicator is going to be putting out a book on the use of sword and shield, probably late in 2015. Essentially, Roland has been doing what I've mentioned above: studying lots of images of sword and shield fighting, and then interpreting them through practice with others.