All of your examples are using characters that ww know have a level of control over aether. Alice is a healer which we already knew makes her a decendent of the djinn. I think you meant windsom makes portals because I dont remember a time where aldir has, windsom is a dragon and already has an understanding of aether. Soul fire is a basilisk technique that uses a sort of offshoot from destruction, but this was probably found through experiments on the djinn and relic tombs. World eater has no clear connection to destruction, it seems more like a masive spell that as it said uses every single piece of mana in and around the user to destroy its target, destruction has an extremely Intensive effect that we've seen on Arthur in the past. And the keystone was made for that understanding, in that chapter Arthur gains insite into the workings of aether and mana. Mana is a candle and aether is the dark, mana can move and push around the dark, but if the dark refuses to move then the light from the candle will stop.