Your investigations have aligned. An old weapon belonging to Saint-14 was recovered by a Fallen long ago. That Fallen, buried in the Tangled Shore, has been twisted into a Scorn Chieftain. Saint's Light signal must be coming from his old weapon. Enter strike "The Hollowed Lair, Memento" and track down the new Scorn Chieftain. Relieve them of their stolen armament of Light.