Trying to come up with a fighting style for Velvet so that I can base her outfit for the maybe-contest around it, and I ended up in kicking-centric martial arts. Because rabbit Faunus. Rabbits kick. I'm so fucking clever.
I remembered Capeoira from my days of actually seriously doing martial arts, and once I refreshed my memory, it was the only option. I can't do Capeoira myself because of my lack of physical strength, but I've seen a lot of it. It was created by escaped Brazilian slaves as a form of unarmed defense. This sort of fighting can easily be used to break someone's neck, so it was certainly effective.
I can imagine Velvet fighting in a style quite similar to Capeoira, maybe with rocket-powered boots or something. Mix a little parkour style jumping and free running in there and she's a force to be reckoned with.
(Incidentally, modern break-dancing was influenced heavily by Capeoira. The video should make it obvious as to why.)