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".
Yeah people do the darnest things to protect themselves and then they drive like they are nuts in a snowstorm. Cars are far more dangerous than guns and we don't have bans on the cars that are involved in the most accidents. Maybe I shouldn't give them ideas but eventually we are going to see that angle taken because it could be very profitable. I think one reason you don't see such calls is because it would be a political disaster, the left being more about easy marks than any real idealogy.