Zin'rokh, Destroyer of Worlds (level 60)

Zin'rokh, Destroyer of Worlds is a two-handed sword with stamina and attack power. Arguably the best DPS and top-damage weapon pre-MC, comparable, if not better than, with items such as and.

Its older brother, drops from the last boss,  in level 70 10-man raid instance Zul'Aman.

Source
This item drops from in Zul'Gurub.