The Sword of Stephen is an object/item and artifact that appears in Uncharted: Golden Abyss.
Nate only uses The Sword of Stephen when you have to touch the sword and rub the paper on it. The symbols on the sword go together to make into a map and this map leads to The Temple of the Serpents. Guerro used the sword to fight off Nate in Chapter 34: "The Revolution Ends". This sword only belonged to Esteban The Moor. Friar Marcos de Niza left the sword into Esteban's tomb.