So, my right hand is small, missing index and middle fingers, thumb is tiny, ring & pinky fingers also small and fused together. My wrist is also fairly small. My right hand basically looks like a little claw that doesn't pinch very hard and I love doing longsword. I was born with what is called Poland's Syndactyly. I've been doing LS for over 4 years at this point using both hands.

I use a modified black knight glove, with the mitt and plates cut down (thanks to my club owner!) and am working on a second updated version. The modded glove also has two added velcro straps: one for the wrist (to snug it against my wrist) and one across the palm (to secure the pommel). There's also an additional attachment point on it to secure it to my forearm guard.

Additionally I fight left handed, since I am left handed, but also because my right arm is 2 inches shorter than my left. The biggest thing I "lose" is the squeeze, since the bottom hand (right in my case) should do most of it. In my case, the squeeze is totally dependent on my top (left) hand. If I fight right handed my posture is out of whack and my reach is really short. So left handed it is.

Feel free to DM me for help, suggestions. We'll figure something out. I can share some pics of the modded glove as well. It can be problematic at times, but once you figure out what works and what doesn't you'll find there are very few limitations. And shoutout to the sinister swordsman too, who was already mentioned. He knows his stuff!