If we stick to edged weapons, then I agree with Rich in using a wakizashi, but also a nice strong dha would do the job even more effectively and requires less skill.
For thoose who want to commit suicide I reccomend the Laz Bichagi. Anyway if you do not have anything else around (try to) use it. Pulling it out from the scabbard is per se a sort of adventure, then if you're lucky enogh and your index finger remains attached to your hand, you can stab your opponent into the eyes with the forked pommel rather than slashing him, 'cos you'd probably miss him.
But keep in mind that if the opponent is armed with a victorinox and is less than 10 meters away, you are doomed.
