While this might be an incredibly broad question, I am struggling to find any solid website/book/video etc. etc. on the subject of armor, clothing, weapons, any kind of such tools of war.
Le Jeu de la Hache and many other martial arts manuals often contain imagery. There's also the Bayeux Tapestry if you want illustrations from earlier in the middle ages
I was able to find a list of known manuals, vast majority from the tail end of the middle ages and Renaissance though. Can't garuntee they all contain illustrations -
https://www.thearma.org/manuals.htm#.Y0CBW6QpBzA
Other than that there's also the Grandes Chroniques de France, which contains number of illustrations of significant battles such as Bouvines, Golden Spurs, etc.
Hope this was of some help :)