When used as weapons, knives usually cause death by exsanguination, which is to say, bleeding. At the risk of being ghoulish, they also (occasionally) cause death by decapitation, pneumothorax or infection. But they never cause death by decompressive tissue disruption, unless they’re WASP injection knives.
The heart of a normal knife is its blade, but not Wasp injection knife. The heart of this gruesomely effective close-in weapon is a CO2 cylinder, which is triggered to vent out through a hollow channel in the blade and into the target.
CO2 injection weapons were originally developed by divers as protection against sharks. They were once known by colorful names like ‘Barf The Magic Dragon,’ and cause frightful injuries to any animal they’re used against. When instantly injected with several dozen cubic feet of CO2, sharks were known to expel most of their internal organs out their mouths (and other orifices) while rocketing to the surface.
These effects are similar to the effects of powerheads or bang sticks, but without the concussive effects of detonating a firearm cartridge underwater.
The WASP injection knife is currently marketed as a defensive knife for divers, hunters and outdoorsmen. I’m not a diver so I won’t speculate as to its utility as an anti-shark weapon, other than to say it looks a hell of a lot better than nothing.
But I’d never plan on using any knife against a bear or mountain lion, unless I had nothing else available. Bears and cats are a lot stronger than us, and can kill or disable a human with a single blow. Unless you’re a fearless badass with a gassed and spinning chainsaw, any distance weapon is preferable to any hand-to-hand weapon when it comes to fighting wild animals. (I would count spears as distance weapons for this purpose.)
The WASP costs $500, which is a lot of money to spend to kill the bear that probably just killed you too. If you’re worried about bears, this kind of money could buy you a new Mossberg 500 Cruiser shotgun, a hundred rounds of 00 buckshot and (more practically) a couple of jumbo-sized cans of OC spray.
If you do buy an injection knife, though, please send me a video? I’ll buy the watermelons.