E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Berserker.
Grandson of the eight-handed Starkader and the beautiful Alfhilde, called bær-serce (bare of mail) because he went into battle unharnessed. Hence, any man with the fighting fever on him.
1
You say that I am berserker. And baresark I go to-morrow to the war.Rev. C. Kingsley: Hereward the Wake.