What's the point with that quite lackluster story in Endwalker?

[KageTokage]

The whole bit about the second legion just being...gone made me go "what" because the notion of an army of their caliber being laid low by terminus beasts seems...silly when even Thavnair with its considerably weaker military was largely able to keep them in check without the aid of the Scions. It's giving me doubts that the remaining Garlean legions are going to end up playing into much of anything if they willing to just write off a legion with ties to House Darnus like that.

It is also mentioned that there were no more confirmed reports of blasphemies so I'd like to think they're not truly done and dusted, especially since communications with the regions occupied by the Garlean legions was limited and there logically isn't much keeping new ones from manifesting if the corrupted dynamis is still lingering on Etheriys for the foreseeable future.

I had a crazy thought that maybe the two elements could end up being woven together into a single threat if some defiant legions found a way to weaponize the blasphemies by deliberately instigating transformations then controlling them with magitek or more mundanely just letting them loose in regions they consider a threat; perhaps finding a method to trigger transformations remotely and at will using auracite or some such. That's probably being overly optimistic considering their seeming desire to just get the Garlean business over with for good, though.

[CrownySuccubus]

IIRC, almost all of the Ceruleum supplies were gone. There was only one group left that still had the skill and knowledge to mine and process it, and they are a group of bottom-caste who are so bitter towards whatever treatment they got from the Garleans that they refuse to work with them.

We're never told exactly what caused the collapse of the IInd Legion, but failed logistics are what destroys most armies, no matter how powerful.