Let's just not mention what Hayabusa has and assume he's fighting with his arms and feet.
No seriously, what the fuck does he have? I could never debate Hayabusa when it isn't mentioned what he has.
Anyway...
The only weapons he would stand a chance of beating Xemnas with, is the Dark Dragon Blade. With the TDS is iffy, though. I don't know if Xemnas would fall under the category of villains with evil intent since he hasn't any feelings...or maybe I'm confusing one thing with another. I'm way too tired at the moment.
A light saber battle between them would be awesome though. Xemnas's dual sabers and Hayabusa's PSMk.II in action. Yeah, good stuff.