What we are seeing is the good, old American berserk in action.
Well, get thee to horse, and make the most of thy time; my berserk here will guide thee past the guards.
I am ordered to send this berserk with a troop of nineteen men to waylay thee.
Of one thing he was assured: somewhere in the dim past an ancestor of his had died in a berserk rage.
“King Harald would speak with thee,” said the man, who was no other than Hake the berserk.
"More likely to have them out on us in some sort of berserk rage," said the man, growling.
A sort of berserk rage possessed him at the sight of that wound.
He is, therefore, the god of the battle rush, the divine force that inspires the athletic frenzy of the berserk.
One never gets used to the bulk and height of these berserk Campanias.
He touched the hilt of his sword, and nodded good-humouredly to the berserk, who did not appear to relish the jest at all.
1844, from berserk (n.) "Norse warrior," by 1835, an alternative form of berserker (1822), a word which was introduced by Sir Walter Scott, from Old Norse berserkr (n.) "raging warrior of superhuman strength;" probably from *ber- "bear" + serkr "shirt," thus literally "a warrior clothed in bearskin." Thus not from Old Norse berr "bare, naked."
Thorkelin, in the essay on the Berserkir, appended to his edition of the Krisini Saga, tells that an old name of the Berserk frenzy was hamremmi, i.e., strength acquired from another strange body, because it was anciently believed that the persons who were liable to this frenzy were mysteriously endowed, during its accesses, with a strange body of unearthly strength. If, however, the Berserk was called on by his own name, he lost his mysterious form, and his ordinary strength alone remained. ["Notes and Queries," Dec. 28, 1850]The adjectival use probably is from such phrases as berserk frenzy, or as a title (Arngrim the Berserk).