(TBAN: Exploring commonalties of therianthropy with past & present cultural practices to reduce stigma & vitriol toward the therian community.)
The name berserker derives from the Old Norse berserkr (plural berserkir). This expression most likely arose from their reputed habit of wearing a kind of shirt or coat (serkr) made from the pelt of a bear (ber-) during battle. The bear was one of the animals representing Odin, and by wearing such a pelt the warriors sought to gain the strength of a bear and the favor of Odin.
To “go berserk” was to “hamask”, which translates as “change form,” in this case, as with the sense “enter a state of wild fury” and one who could transform as a berserker was typically thought of as “hamrammr” or “shapestrong”
As the Ynglinga Saga puts it,
"Odin’s men [berserkers] went armor-less into battle and were as crazed as dogs or wolves and as strong as bears or bulls. They bit their shields and slew men, while they themselves were harmed by neither fire nor iron. This is called “going berserk.”
In the biting or casting away of their shields, we see a reminder that their ultimate identity is no longer their social persona, but rather their “unity with the animal world”.