Quel'Delar, the Sister Blade is a prismatic blade forged by the night elves[1] and the five dragonflights along with its sibling, [Quel'Serrar]. Quel'Delar serves as an idol of opposition against the Scourge, and the elven factions of Dalaran would therefore like to see the blade play a pivotal role in the assault on Icecrown Citadel.
Players are able to embark on a mission to assemble the sword and either wield it themselves or trade it with their respective Dalaran faction for a weapon they can use.[1] Doing so will reward the achievement The Sword in the Skull.
After its creation, the sword was given to the quel'dorei[2] and passed down from father to son until it was wielded by Thalorien Dawnseeker[3] against the trolls and the Scourge. Thalorien eventually fell at the hands of Arthas' lieutenants and the blade was subsequently brought to Icecrown by Lana'thel, one of the followers of Kael'thas. Lana'thel originally intended Quel'Delar to be an instrument of vengeance, but after her own demise began to harbor hatred for the sword.[1]
In the Halls of reflection, the character must "subdue" Quel'Delar. Quel'Delar fights much like a warrior, using Bladestorm, Heroic Strike, Mortal Strike and Whirlwind. He not only can be disarmed by a warrior's [Disarm] ability, it has been reported that other methods might also work. (Note that where disarming works, it does not automatically result in victory.)