I love these trips through history. Maybe Cindy Sheehan can add it to her Department of History. lol Some knives are inherently dangerous? Nooooo. I just can't believe it. Sometimes you have to wonder how many moths have set up residence in the minds of such politicians.
Well, there was a Russian knife called the pilum that was available back in the 80's that probably did qualify as inherently dangerous. When you activated a lever a powerful spring inside would actually shoot the blade out of the handle at a respectable velocity. From what I've read of it though you were more likely to accidentally discharge it than you were to actually shoot it at anything.
Interestingly they are now extremely illegal and you'll do more time for having one than you would for possessing an illegal machinegun. You can look up the details by googling "ballistic knife".