Though I only watch playthroughs, I can wholeheartedly say that Elio's an <Anemo> user by default. It pretty much fits into his freedom and independence schtick that he has goin' on since childhood (even if it's pushed onto him by his oldest brother), which he inevitably achieved post-graduation. Not to mention it emboldens the carefree and adventurous parts of his personality.

As a swordsman, his weapon of choice is a <Sword>. Not to mention, he would be a five-star (⭐⭐⭐⭐⭐) character.

Jasmine would have a Dendro Vision with which she would create Vines to fight with

Andres probably a Pyro vision and he would have a brawler type playstyle

Fausto I’d say either Pyro or Geo, Balei would be Hydro no doubt, and Damascus I’d say Geo or Dendro! (I don’t play Genshin but I think I got the names right??)

Kingston: electro sword (maybe cryo instead of electro idk qwq)
Ruth: Cryo Bow
Mirajane: anemo Catalyst
Sadie: visionless and bitchless

Pyro LOL Going further than that, I think Briar would be a pyro polearm (:

Estella - Pyro

Artemis - Electro

Darius - Geo

Gareth - Anemo