So, only knives that have no legitimate purpose other than to cause harm are banned? A switch blade is banned while a filet knife is not. Both knives are equally capable of being tools for murder, but the filet knife can be used in hunting, fishing, and cooking. All legitimate uses. While the switchblade isn’t really feasible in any scenario outside of a fight.

It’s not the presence of illegitimate uses that gives rise to the ban. It’s the absence of legitimate uses.