Going into the first level 80 dungeon expecting to fight Emet Selch as its final boss, I thought to myself "haven't we been here before? Am I supposed to feel threatened?"
For indeed we HAVE been here twice before
- we fought Lahabrea together with his lady friend, and won
- we fought Elidibus wearing Zenos' body, and won

Both of them are of the highest tier of Ascian, just like Emet Selch. So I assumed that if anything, this would end up being significantly easier than both of those previous instances. We're only fighting a single Ascian with no aid after all - Emet would fail to take us seriously because we're on the verge of going feral and lose to us. In a last effort, he would then pull the lightwardens out of us and combine them into some kind of super sin eater (like, say, SIN), which would then serve as the final boss of 5.0.

Imagine my bewilderment, then, when Emet started talking about how overpowered he is before transforming into an edgier version of Nightmare from the Kirby series.

Soooooo.... did I miss anything? Was there any explanation for why Emet is so much more powerful than his colleagues?
Unless canonically that entire fight was an ungodly stomp in our favor, it doesn't seem to make any sense.