From WoWWiki
Sulfuras, Hand of Ragnaros is a Feat of Strength achievement, granted when you have aquired the legendary mace [Sulfuras, Hand of Ragnaros]. It is not retroactive, meaning that if you have had the weapon before Patch 3.0.2 and deleted it, you won't have the Feat of Strength and have to reaquire it if you wish to have this Feat of Strength.
Locations
Sulfuras, Hand of Ragnaros is crafted by a Blacksmith with a minimum skill level of 300. The blacksmith can obtain the pattern by turning in one [Sulfuron Ingot] to
Lokhtos Darkbargainer in the Blackrock Depths. Crafting Sulfuras, Hand of Ragnaros requires an [Sulfuron Hammer] which is also crafted by blacksmiths, and an [Eye of Sulfuras] which is a rare drop from Ragnaros in the Molten Core.
External links