Knives of a certain design (switchblades) and lengths? Absolutely.

You don't need a switchblade to kill somebody. A steak knife or a filet knife will do just as well. Should we ban those, too?

We should (imho) enact reasonable regulation that balances rights with citizen safety in a country where people need to be told not to fill plastic bags with gasoline and there is a widespread belief that there are microchips in vaccines.

Screwdrivers, tent stakes, bottles of propane, battery powered circular saws... you can kill somebody very easily with just about everything they sell at Home Depot, and many of them are far more effective than a knife.