William Wallace's Claymore

Origin
This Claymore, famously known as the Wallace Sword, was reportedly wielded by Scottish rebel leader William Wallace during the wars of Scottish Independance. Actual reports of its use are sketchy at best and it may pre-date Wallace. The blade contains some Nordic designs that were omitted from the replica left in the Tower of London.

During a short-lived stint as a Warehouse clerk, one agent released information on several artifacts to a noted game developer he Sai'x 's weapon.

Effects
When held, the wielder enters a state of beserker rage, allowing them to mow through enemies and ignore large amounts of physical pain. The bloodlust subsides only when there are no foes left to strike down, though the definition of 'foe' is a bit blurred. The haze caused by the rage makes it difficult to distinguish between friend and foe, making any living person a viable target.

For unknown reasons the effect seems to be amplified by the cycle of the moon, leading some regents to suspect the sword, or at least part of it, has ties with Nordic lunatic beserkers.