When the final Boss jumps to the platform you are standing on, he will lunge at you with his sword. Right before he swings it, dive out of the way. If done correctly, he will trip and fall. Quickly grab his sword from the ground next to him before he gets up and start attacking him with it. Note: The sword can be used to hit three consecutive times by quickly pressing RT(3). If he manages to get away, he will summon his sword back to him. After this happens, just wait for him to jump back onto your platform and repeat the process.