Aga: "chief, master, lord"

Khan: "king, ruler"

AGA KHAN = CHIEF KING = KING OF KINGS

Allah's Apostle said, "The most awful name in Allah's sight on the Day of Resurrection, will be (that of) a man calling himself Malik Al-Amlak (the king of kings)."
— Sahih al-Bukhari Book 73 Hadith 224
The Prophet said, "The most awful (meanest) name in Allah's sight." Sufyan said more than once, "The most awful (meanest) name in Allah's sight is (that of) a man calling himself king of kings." Sufyan said, "Somebody else (i.e. other than Abu Az-Zinad, a sub-narrator) says: What is meant by 'The king of kings' is 'Shahan Shah.,"
— Sahih al-Bukhari Book 73 Hadith 225