Well first off, before I work too hard to defend his interpretation of berserkers(which I think is only true to the viking age), I'll bring our attention back to the fact that the primary sources we have to draw on in this matter are poems. So being as you are familiar with kennings, there isn't much need to dwell on how one thing may mean something completely different from the literal reading, or perhaps have numerous meanings.
You know i've heard what that blokes stating before, that Berserker means Bear shirted, but from my limited knowledge of Old Norse that would be Bjorn Skirt or Sark.
Bjorn is the literary word for bear, and was a very common name. Like many names today, diminutive forms existed, in this case, Bersi.
As for sark, well it's arguably pronounced the same as serk. I feel pretty comfortable saying that the divergence in spelling is something that happened over time.
It's funny that he mentions Egil's Saga as I would say that maybe the Skallagrimsson was a battle rager, he is known for his black moods and then bouts of violence, so intense that he killed his first man at the age of eight with an axe after a heated bout of some kind of ball game like Hurley.
While I think that Egil Skallagrimson was a real person who did many of the things mentioned in Egil's Saga during his lifetime, I feel rather well convinced that the character depicted in the saga is largely fictional, and serves to convey a mythic/literary theme. I think Egil(as a character), is primarily a vehicle for communicating the strengths(and ultimately, the failings) of pre-christian virtue as it was conceived in the viking age. He just checks too many of the boxes, berserker(which is commonly translated as 'shapeshifter' in this story, and I would argue accurately as he encounters a guy shapeshifted into a bird later in the story), skald, rune writer(and thus spellcaster, as we see in his encounter at the farmhouse involving the guy who wrote runes not knowing what they meant), and indomitable hardass.
But there are people who have made entire careers out of coming up with different arguments and interpretations for the story, so there's no telling.
Personally my own take is that it was mainly a form of psychological posturing, but that there were actual battle ragers, men who drive themselves into a killing frenzy and could not be put down easily like Colonel H. Jones in the Falklands and many other military folk through the ages.
Well yes, and I don't agree fully with what lindybiege is saying, at least not in spirit, even if he's presenting a valid argument in his own context. There were people who entered altered states of mind for the purpose of killing, but I think that it was in a manner which wildly diverges from
simply sitting down and taking drugs or having a propensity to get super pissed and wild.
Because...
...you're correct in lindybiege being incorrect about his saying that berserkers have nothing to do with celts, or well sort of. Because it's accurate to say that berserkers have nothing to do with Celts. However, it's only accurate in a legalistic sense that relies on semantics.
But, I'm very glad you brought Cuchulain up, because it makes it easy for me to sum my argument up pretty neatly.
See, Cuchulain's battle rages are accompanied by grotesque mutations which are in my view a psychological metamorphosis which Cuchulain(and all human beings for that matter) must undergo to confront the experience of life. The reason I feel that the 'bear-skin' interpretation is more valid is precisely because we see this theme of transformation appear across pretty much all European mythologies and extending far beyond that. People would wear the skin of a fierce animal so they could take on the spirit or psychological aspect of that animal, and *sometimes* that meant getting super pissed, but it would be reductive to say that the entire practice *was* getting super pissed.
Which could be construed as pedantic to say so much about, but even within the very specific context of game design we're having this discussion in, I think it would be really neat to see somebody convey the distinction between a pagan bear shaman and a beefcake that throws fits.