If I'm correct one of the bigger reasons he went to Azy in the first place was because of the Warring Triad, IE a GIANT WELLSPRING OF AETHER to use from himself. The Ravana EX quest also mentions him wanting to take the Warring Triad's power/aether for himself for his conquest of Eorzea (and I think something about Bismark just wanting to eat them? Not sure there.)