I always thought that "might" was always represented as "divine essence" that permeated the universe before the big bang. The power that makes gods... godly? Yeah. Gods are the only beings that are inherently interlinked with that power. I always wrote as if Ull was aware of said essence, and I have stated so in my posts from time to time (or implied at least).
IMO When gods make something mortal a hero, they unlock within it the ability to sense/use said divine essence, albeit not with the same capabilities as a god would. They are confined and limited to what the god gives them. The same thing happens to demigods, but they possess better prowess in manipulating this power and are not as limited as heroes, only within their domains/portfolios. A god, contrary to a demigod, can manipulate their surroundings freely even if what he wants to do isn't a part of his domain/portfolio.
A single god can create a planet for example, and won't really need much might to do so. A demigod (not unless they achieve godhood) cannot do that, even if they use might.
A form of "bestowment" of might, imo, is the gifting of divine weapons/armor/other tools to lower beings from gods. Whether those items might reserves deplete with time or not, it's up to the players to decide really. Forcefully leveling up a hero/demigod is like having the god channel the divine essence from within them to the said recipient, fundamentally altering them so that they can sense/manipulate said divine essence better.
I don't know if you understand what I want to say... And anyway, this is all my assumptions thus far, since not much has been canonised by Kho/Cyclone pertaining the whole thing.
EDIT: Also, as gods are basically born from this essence, the level of purity of essence they possess is the highest possible. This is why if a hero or demigod gets their hands on some kind of godly part (blood, crystalized essence, etc.) and absorb it, they can level up instantly.
When Loki mentioned the
Aether stuff, that's basically what I had in mind as well. As for Amartia naming it as "the Fifth Element" and whatnot, I don't know if gods would describe it as such. Astarte thought it was "just there" and she could "just do stuff" so yeah. Specifically designating as "Aether" would probably be just Amartia trying to theorize how this stuff works.