Black Menace

Black Menace is a one-hand dagger 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 Southshore in Hillsbrad Foothills. To complete the quest, you must slay High Inquisitor Whitemane, Scarlet Commander Mograine, Herod and Houndmaster Loksey, in Scarlet Monastery.