Well if this was in the KH world I would just be like: "Ha. I command the darkness now." And summon a crap load of heartless to jump on him. Then while he was on the floor I'd grab the masamune and stab him repeatedly in the face.

If it's in the real world: "F*** off I'm trying to kick your A** on this game." Then stand up and kick him in the groin and watch him crawl about on the floor in pain. Then pick up that masamune which he conveniently dropped and stab him repeatedly in the face with it.

It's a win-win situation.