Sword of Corruption

Sword of Corruption is a one-hand sword that is most often sought after by Rogues.

Source
This item is a reward from the Alliance quest which starts with Raleigh the Devout in Hillsbrad Foothills. To complete the quest, you must slay High Inquisitor Whitemane, Scarlet Commander Mograine, Herod and Houndmaster Loksey in Scarlet Monastery.