Not that I agree with this point of view, but I think that some people might see it as that the weapons for melees (or even the shield or harp) are helping not only the player who is wielding them, but improves their performance when fighting serious stuff with said groups, and thus helps the group as a whole. Whereas weapons like Hvergelmir and Gambanteinn are seen more as weapons that are just for messing around with on your own or with friends, and not something for use in serious fights.