in MN the knife law has something to do with the length of it, and how it unfolds.
and HOW you carry them.
but you can own any million blades you want, just cant carry it around.
even gun laws are similar.
you don't need a gun license or even an ID to buy any machine pistol or assault rifle from a gun show.
but you have one in your car, or a simple handgun without a license in public and your in trouble.