Yeah, I've been looking for treatises on sword and buckler so you could get a better handle on the forms. I haven't been able to find a good link, but you can get a PDF translation of Royal Armouries MS. I.33 easily enough.Fencing definitely counts - fencing has a vocabulary (parry, thrust, etc) that describes motions with swords. Obviously, the style of fighting here is different, but again, what you're trying to do is to visualize the steps of the fight yourself, and then convey that in words or pictures. You can maybe get posable figures (artists use them to get anatomy right, but you can probably use any action figure that bends enough). Or you could find a video that shows the right type of fight, and then use timestamps to pull out individual moves. These are just suggestions, though - whatever works for you to convey your ideas is fine.
In the top series of images, we see a pitcher throw a baseball. The three poses convey the motion without needing steps in between to convey the idea of what is happening.
I guess these are meant to be 'super hero poses' or something but the idea here is that you could pose a figurine at any step in the process and show how they are fighting - especially if you had two figurines.
This series of sketches shows a bunch of different poses with a spear. Nothing about it is fancy or identifies the character (though some are taller, some heavier, etc). The important detail is the way the body is moving and how they are holding the spear. If you could find a similar series for sword and targe, you might be able to use those to tell your story.
To get the right vocabulary to describe something in words rather than visuals, looking at the manuals for this kind of fighting might be helpful.
(Excerpt from 'Medieval Swordsmanship' by John Clements)