Trifter has a pretty neat post about some gruesome weapons from the past. I like this one, the Hawaiian Throwing Axe, made with ... shark teeth!
This Hawaiian Throwing Axe was a deadly hand held weapon that could be used at both short and long range. This weapon was made out of wood and shark teeth had the power to take men's limbs off. This weapon was mainly used when opposing Hawaiian armies closed upon each other. They were then thrown at the opposing troops to help soften enemy ranks before close combat. They could also be used in hand to hand combat and had the muscle to rip open skin as if it was butter. This was a very dangerous weapon and is not something you would want to go up against.
Link - Thanks jon jason!