Originally Posted by
Cenerae
After beating Fordola, we knew that Zenos had the same source of power. But we also needed a special device to weaken Fordola so we could best her in combat. We employed no special tactics against Zenos, we just beat him down like anyone else. Which implies that Fordola is far stronger than Zenos (which is not how the story presents it).
As for Omega damaging Shinryu heavily, I want to point out that a relatively long time went by in game time between Omega and Shinryu fighting, and us getting to fight Shinryu. It certainly didn't look very hurt when we went to battle it, and I doubt that it being imprisoned by the Garleans had done more than make it really angry.
I'll take your point about the eyes, though. Though I suspect that Shinryu would have tried to raid somewhere with a lot of crystals, were it running out of aether to stay corporeal.