The Duel on Darth Revan's Flagship was a confrontation during the Jedi Civil War between the Dark Lord of the Sith Revan, and Sith apprentice Darth Malak. It took place in Revan's flagship. The lightsaber duel resulted in Malak's defeat and the loss of his jaw.
At some point during the war, Malak openly viewed his Master as being soft, causing tension between the two that culminated in a lightsaber duel.
Malak's jaw was removed by a lightsaber strike from Revan, and Malak was forced to wear a large metal prosthesis cover over where his jaw had once been. A vocabulator allowed Malak to talk, but his voice now reverberated with a gruff electronic tone.
- Knights of the Old Republic Campaign Guide