Butterfly knives are illegal in my state, that qualifies as a banned weapon... I only have one but it's just a cheapo, I never carry it or use it except for playing with it...
It is really too bad my little K-bit is illegal because I do carry that. Two things that push the letter of the law... don't quote me here,eh...I'm going off my memory here. One is the ring, it's steel and could be considered a "knuckle" which is illegal and two, it's in my pocket. That's the tricky part because it's a fixed blade. Exposed it's fine, folded in the pocket is fine. Fixed and concealed... no no.
Mine is a mere 1 inch blade. Nothing like a real knife. Still a banned weapon if you cross the wrong LEO at the wrong time in the wrong place.
