The answer also was for OP, but it did drift on yours ahah

As for Meteion, I think that's why she *has* Aether : she was created as an aetherial being, with very little aether though, and in away to make her as attuned to Dynamis as possible. She's not literally made of it though, or at least a "proto meteion" isn't created with Dynamis, but she does use its energy on a day to day basis.
As Hermes said, just not having aether isn't enough to be an entelechy, so it probably took a lot of trial and error to get there. He kinda had the Elpis flower to retroengineer.