Mordakhesh, known as the Shadowsword, is the prakhutu of the Overlord Rak Tulkhesh, the Rage of War, and the greatest of the Zakya. He is a legendary commander, and sits on the Bleak Council of Ashtakala, working to free his overlord from it's containment.
It's possible that Mordakhesh had a hand in some of history's bloodiest conflicts. The Dhakaani have stories of a mysterious figure teaching them to make their first weapons, and Malleon the Reaver's conquest of Khorvaire's goblins was motivated by a shadowy advisor.