Ionian Tryndamere and Katarina skins based on Yasuo's childhood friends.

They would have wind related particle effects added to some of their abilities and look like their depictions on Yas' promo page(link provided). I felt like looking back at that and noticed that the descriptions also kind match.

IK that Yas is supposed to be the only one of them to master wind techniques, but all of them probably knew a trick or two.

Garen and Akali are also candidates since they fit into the same general archtype of brute swordsman and agile light weapon dual wielder. I would however choose Trynd over Garen because the prevalence of crit and extra crit chance in his kit would help cement the link to Yasuo, same for Kat's pure "manalessness" rather than Akali's energy.

Maybe a Master Yi skin based on Yone would be cool too?

PS. Anyone know the names of those 2?