Revelations from Patch 3.5

[Naria]

"Bahamut full power" (The one that destroyed FFXIV 1.0) had thousands of years to charge in a moon-sized container full of dragon batteries.

Ilberd's thing did not. Unless he found some way of gathering huge amounts of aether in a very short amount of time that alluded even the Allagans, it's unlikely that it would have compared to full Bahamut.

Granted this is basically speculation but if it is Rhalgr then he has been worshiped for millennia as well--longer than Bahamut was trapped in that moon, and likely by a much larger population. From my understanding it was the faith and not "dragons are a great source of aether" that was empowering Bahamut. I can't go look through the CSes to confirm atm since Aether Datacenter is (ironically) down.

If it isn't who I think it is then yeah my argument doesn't have much to stand on.