What about regular bows? The exception for crossbows is certainly a bit odd. Don’t entirely get the ban on pepper spray (or similar), unless they just don’t want it to get used against police. The taser one seems to be in a similar rationality.
As for regular bows, it's... Tricky. I'm having a little difficulty finding a clear answer. As far as interpretations go, some people say "yes, it's a weapon" while others say "no, it's a toy". For legal documents themselves, I'm having a dickens of a time qualifying and dating the precious few things that pop up... Or, rather, having a hard time finding the motivation to do so. God damn, lawyers use a lot of paper to say very little.
Regardless, it is illegal to hunt with bow and arrow in Norway, so you're probably gonna have a hard time explaining why you have one.
As for pepperspray/tasers, yeah. It's either a matter of them getting used against the cops, or it's a matter of the nanny state just assuming that we'd probably put our eye out if they let us play with things like that. Probably the vs. police argument, but you can never really tell with Norway.
This leads me to a story about meeting the father-in-law of one of my old school friends. The fellow took a liking to me rather quickly, and was deeply excited about having someone with an interest in guns (and a bit of military experience) to show off his collection to. He had a couple high-powered carbon nanotube hunting rifles (perfectly legal, although it's expensive as all hell to go through the registration process for each weapon, not to mention a mountain of paperwork), a basic 9mm for the firing range, and a Nazi-produced .45 pistol with the worn-down Reichsadler etching still visible if you looked at it closely.
Later, encouraged by my attention and curiosity, he showed me "a little secret, just between us", which was a self-defense pistol that fired teargas capsules slightly larger than a pea. The capsules would break apart upon hitting clothing, and the gas would then irritate and hopefully discourage any would-be assailants.
Of all the weapons he'd shown me, this was the only one that was illegal to own. The non-lethal one. I found that kinda funny.