So, according to Norwegian law, it is strictly illegal to own or use weapons such as blowpipes (for the firing of darts or other objects), slingshots (particularly funny because the Norwegian word for such can be directly translated to "bouncy pea"), electroshock weapons like Tasers (ranged or touch), pepperspray, "fighting gloves" (not sure what this means, specifically), shuriken, any sort of knvies, etc. etc... "Or any other particularly harmful weapon that does not have an 'honorable' use or can be seen as being violent articles (lit. 'violence products')".
...Except crossbows. You can own and operate a crossbow if you fulfill the standards of age, sobriety and responsibility, and get permission from your local police chief.
Also, technically you can kind of loophole it by carrying a tool of some sort, since it fills an "honorable" use. Bouncers and doormen (almost wrote doorknobs) seem to go for those nice heavy MagLite flashlights for their improvised weapons. So, wooden self-defense pocket sticks or some pepperspray? Illegal. Steel wrench? Yeah, sure.
(note: As with most laws here, there's a lot of interpretation being done by the legal system... If you're out on the town with a hammer in your pocket, nobody's going to let you off because it "serves a purpose". Probably).
Laws, man...
But crossbows were banned by the pope! You'd be excommunicated if you used one! Checkmate!
Which is a moot point if you are not catholic. And according to the wiki 71.5% Norwegians are Lutheran.
The worst part about weapon restricting laws is, that they tend to be contraproductive.
In order for such law to be effective either:
A) The weapon being restricted has to be difficult to obtain illegaly.
or
B) The sentence for owning it has to be worse than the sentence for crimes commonly commited with its use.
If neither is true, then people intending to commit crimes have no reason not to get it. If they get caught with it, it will not be much worse than getting caught without it in those circumstances.
On the other hand, people, who intend to obey the law will not have such weapon and will be at a disadvantage against someone with it.
Oh, and "particularly harmful" weapons with no use other than fighting can be created pretty easily.