As I’ve read more into Viking culture, I’ve noticed conflicting definitions:
berserker: ber(bear) and serker(skin or cloth) and thus believe to have gone into battle naked without weapons
That the latter interpretation (1) is a wrong interpretration and that instead these warriors went into battle with the spirit (‘fylgja’) of a bear but clothed with weapons. Which definition is considered correct?
I always assumed that they wore literal bear skins, neither naked nor just the “spirit” of a bear. And whatever they were wearing (or not wearing, as the case may be), they definitely used weapons.
Wikipedia quotes the “bare-shirt” etymology as being sourced to Snorri Sturluson. That would certainly explain why it is so popular, even if it were wrong. It also says it’s been abandoned. My Norwegian dictionary only lists the “bear-shirt” etymology, and as far as I can tell, though I speak Norwegian, not old Norse, is that that makes more grammatical sense as well. The grammar of Norse had a lot of differences from modern Scandinavian though.
Still I see no reason to doubt the Wikipedia quotes here. If there was a large contingent of experts in Norse disagreeing about this I’m sure they’d add the dispute to the article.