Knives have gotten more and more restricted in this country, in many cases they're more restricted than firearms. How does this make sense? Well, I guess there's no big knife lobby, but still, I carry a knife (and it's a switchblade omg!) at all times along with a firearm, and the knife (and being an automatic it's ability to operate one-handed while my other hand is holding something) have come in handy many many times, but never as a weapon. I've never had to draw my firearm apart from practice and competition, thankfully.
Honestly it makes no sense to me that you can carry firearm across most of this country but if you have a knife over 3 inches or double edged blade or automatic opener in many, or most of those states you are screwed, clearly a violent criminal.