Why are there laws about them? My guess would be that there are two factors at play. First -- I bet someone along the way was carrying them with nefarious intent. As an example of this sort of reaction, in VA, it's now specifically illegal to carry machetes concealed because gang members were doing so, and using them to assault people. Second -- there's long been a propaganda effort aimed at some martial arts weapons. Many years ago, 60 Minutes did a piece showing how dangerous some martial arts weapons were. Black Belt magazine responded with an editorial where they showed that many household items were at least equally dangerous, subjected to the same test of "deadliness" that was used on TV. Unfortunately, politicians often respond to the noisiest folks, not the folks who are most correct or have the most reasoned viewpoints.