Nights Bane (3.5e Equipment)
From D&D Wiki
A rare weapon ultimately found only in a deep dungeon, a GM may use this weapon to reward a party member as a climax of a campaign, the weapon may only be wielded by a medium sized creature. This weapon is made of Obsidian and pure darkness and was said to have being forged by demons. A powerful wizard is once said to have obtained it and enchanted so that only a medium sized creature could wield it, though the reasons why he did this have never being discovered. in order to wield this weapon, the character must be a minimal of level 15 with at least 8 levels in Fighter, Paladin or Ranger, and must have a proficiently with exotic weapons. It is also impossible for this weapon to be destroyed by anything less than a god.