I would agree, plated tes, but you;d be screwed if you were in a Gi, which is why the whole tactic would be not to get hit. Beheadings are done with blades, I'm sure they could cut well, but if you were aiming for a limb, you;d probably have to go for the joint, like at the clavicle...I don't think in air, one would be able to build up enough momentum to hack through the middle of bone bone like a butcher knive on a cutting board though.
And if your gonan go all martial thats why you should equip a katar, or my favorite word...suwayyah!...hehe, I could say that all day..SUWAYYAH!
Katar - Wikipedia, the free encyclopedia