It's about the potential. That of a gun is much higher than that of a knife. Also, what use would an ordinary civilain have for a gun if it takes training to be able to use it? You don't seem to be arguing in favour of your own point.
Roel, in the States, quite a few "ordinary civilians" own guns! They buy them for hunting, (yes, with pistols!), target shooting, and oh yeah, protection. For the most part, you'd never know it to meet them, or to talk to them. Unless, of course, they're wearing their Glock Shooting Sports t-shirt and ball cap! :bang: