Majesty

Majesty is Disc 2, Track 16 on the Xenoblade Original Soundtrack. It plays during these cutscenes:
 * Shulk and Reyn reaching Kneecap Hill in the Tephra Cave area, looking at Mechonis
 * The Monado III receiving the power to kill gods and Zanza's last words after the final boss battle at Sentient Genesis in Memory Space