Legendary Items
Everyone's heard of epic items - those purple colored goodies that fetch absurdly high prices on the auction house. Epic items may be obtained from random world drops (if you're very, very lucky!), crafted items (the recipes will either be rare drops or require faction grinding to obtain, and the required materials to be time-consuming and difficult to acquire), or drops in raid dungeons like Zul'Gurub, Molten Core and Blackwing Lair. However, more rare and desirable than even the best epic item is the legendary item - only two of these orange colored items are known to exist in Azeroth - Sulfuras, Hand of Ragnaros and Thunderfury, Blessed Blade of the Windseeker. Acquiring these items is a task in itself - both require two very rare drops from Molten Core, as well as having long quests and materials involved in their creation. However, there are rumors of a third legendary item known as the Ashbringer.
Just because no one has ever acquired an Ashbringer is not proof to some that it does not exist, and Blizzard has left just enough clues in the game to keep players searching. One of the Shen'dralar in Dire Maul mentions the Ashbringer, with hints that Prince Tortheldrin knows more, and might be willing to tell of it. A new NPC involved with the Ahn'Qiraj scepter quest, Narain Soothfancy, mentions the Ashbringer as well. But is it a real item, or merely legendary itself? Well, you'll have to read up on the rumors and decide for yourself. First, check out this old thread about a possible quest item, Timolain's Phylactery. Then, there's a more recent rumor by someone claiming to have found a quest chain leading to the Ashbringer. Only time will tell whether this is real or just a hoax.
