The quest you want is given to you by Seril Scourgebane in Everlook, located in Winterspring. Like Drizz said, you gotta be 50 and I think you need smithing at ~275 before he'll give it to you.
The qst brings you into Stratholme, where you need to click on some plans to spawn the swordsmith guardian (or whatever his name is) near the baroness. Once you defeat him loot his insignia and return to Everlook to turn in.