The WASP Injector Knife was designed to kill in a particularly gruesome but effective way. It's marketed as a defense against deadly sharks, wildcats, and bears. From the product site:

This weapon injects a freezing cold ball of compressed gas, approximately the size of a basketball, at 800psi nearly instantly. The effects of this injection will drop many of the world's largest land predators. The effects of the compressed gas not only cause over-inflation during ascent when used underwater, but also freezes all tissues and organs surrounding the point of injection on land or at sea.

Watch what it can do to a watermelon.

Imagine what that would do to a human body! The first person to use this in a crime will be undoubtedly be in the headlines worldwide. The company recommends it as a weapon for military and special police use. The knives are priced at $379.95, with accessories and a higher-priced engraved wood handle knife also available.

I hope I never have to see the WASP Injector Knife used against anything other than a melon.