As you begin, turn to your left a little and perform a Chain Yanker on Sensei. The moment he's stunned, get to the skinny ass and take him down ASAP before Sensei recovers.

Once he's down, pick up his cutlass and use it to kill Sensei. Start with a few light attacks first (press []) to stun him a little before you go for launch attacks (press /\). Before the cutlass is destroyed, throw it at him and that should do it.