Found in Irenicus' dungeon.
A Piece of the Equalizer
This is a part of the Equalizer, a great long sword forged long ago as a tool for balancing the powers of the universe. Also known as the 'sword of neutrality', it did greater damage the further the target's alignment was from True Neutral. The Equalizer was last rumored to have been wielded by the elven hero Alaine Greenleaf, who was lost during a voyage to the Underdark. Other rumors have, however, proposed that the blade's pommel gem was stolen by an escaped slave who returned to the surface world.