Stygian Iron

Stygian Iron, like celestial bronze, is a metal capable of killing monsters. However, Stygian iron is much rarer. Stygian iron, when being forged, is cooled in the River Styx in the Underworld, producing a keen, indestructible blade. Because it is cooled in the River Styx, Only the children of Hades can use it because of its availability in the Underworld. One large difference between celestial bronze and stygian iron is the way they kill monsters. Celestial bronze turns the monsters to dust, but Stygian iron sucks their essence away until they are killed. Another thing about stygian iron is that it is usually consecrated with a oath sworn upon the River Styx. One notable user of stygian iron is Nico di Angelo, in the form of a short sword. In The Last Olympian, Hades has a double-edged stygian blade etched with silver.