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

[Kyohei]

This all comes down to their sheer power, rather than tempering, per se. Lahabrea and Nabriales took it a step further with their zeal and that I believe is why they brought it up - Lahabrea in particular let his identity fade through extensive body-hopping, and so the idea seems to be he was changed by it unlike Hades. Elidibus sustained memory loss but his guiding duty, stemming from the Convocation, appeared to at least allow him to retain enough of his identity to avoid going the way Lahabrea did.

Not sure if it really was wise to depict them as tempered instead of just letting them have their very own different personalities without any influences other than their own convictions and duties. In a way it makes things less interesting.