The Ashbringer
The Ashbringer quest is currently incomplete, but this is our best guess.... First you must aquire the Corrupted Ashbringer from the undead Highlord Mograine in the Naxxramus Necropolis. You must then uncorrupt the sword using a holy place or some sort of holy item, possibly also aquired in Naxxramus. Currently however it's most likely not possible to uncorrupt the sword. As indicated in an interview with Jeff Kaplan, the Ashbringer storyline will only continue, but not be finished, in patch 1.11. You may notice that the DPS for the corrupted sword is more than it's supposed legendary counterpart. This is most likely explained by the fact that the Corrupted Ashbringer is "in play", meaning it is obtainable by players on all servers. The legendary sword is however, not. All we know of the legendary is what has been glimpsed by peeking in data files and random encounters with GMs who have it equipped. The datafile for the legendary was incorporated into the game's MPQ files over a year ago, (by accident? who knows). In view of the apparent DPS disparity between the two, it is highly probable the legendary will receive a revamp of it's stats and equip effects before it is formally implemented.
Ashbringer Binds when picked up Unique Two-Hand Two-Hand Sword 201 - 247 Damage   + 30 - 50 Holy Damage   (88.0 Damage per second)   Requires level 60   Chance On Hit : Blasts a target for 700 Fire damage "Blade of the Scarlet High Lord" Corrupted Ashbringer Binds when picked up Unique Two-Hand Two-Hand Sword Speed 3.60   259 - 389 Damage   (90.0 Damage per second)   -25 Stamina   Durability 120 / 120   Requires Level 60   Equip : Inflicts the will of the Ashbringer upon the wielder. Equip : Improves your chance to get a critical strike by 2%. Equip : Improves your chance to hit by 1%. Chance on Hit : Steals 185-216 life from the target enemy. "Blade of the Scarlet Highlord"