Elemental-Imbued Weapon

The Elemental-Imbued Weapons were the result of the Dark Irons and Twilight's Hammer's increased collaboration. Using the knowledge of the cult, the Dark Iron dwarves were imbuing their weapons with elemental powers, outfitting the Anvilrage legion with these fearsome new weapons.

Source
Dropped by Dark Iron dwarves in Blackrock Depths while on the related quests.

Objective of
Must be broken while standing next to the Black Anvil in Shadowforge City.
 * Weapons of Darkness (Alliance)
 * Weapons of Darkness (blood elf)
 * Weapons of Darkness (tauren)