in denmark that law worked wonders and was later expanded so you are not allowed to have a screw driver on you if you are not needing it for some work. so at party disctricts or railstations no one can have stuff that can be used for stabbing.
whats the worst this law can do? a few less assholes with weapons.
nah. dont think so. if groups of people meet it can get heated and the less likely someone has a knife or screwdriver the better. sure, any time any one can commit any crime with whatever. but lowering the chances of getting stabbed is always a good idea.