We’ve mentioned ARMA: Association for Renaissance Martial Arts before and since swords have been brought up again, it might be worth your while to seek out the sparring videos on Youtube.
In the meantime, watch these two spar with with some zwihander wasters. They’ve even put it in slow motion so you can see what they’re doing.
For more information on Renaissance and Medieval martial arts bookmark their webpage and this site: Wikitenaur because it contains the largest collection of handbooks and information by expert researchers on the internet. It’s also free.
Advice and suggestions for writing fight scenes.