The banner wings at current look kinda cool but I just don't find them cohesive with his look.
They should really be his ordinary wings from World Ender, just furled neatly at his back. Surely there is some bit of animation that Aatrox already has where the wings are just unfurling from his back plates? If not it that should be added.
This way the whole thing would just make more sense, it would add to the visual at presentation of Aatrox. The way the banner wings are now is a fanservice - while nice does not add to his look but distract from it. The fact they are a toggle highlights that they aren't needed.
I think it should look excellent if Aatrox had furled wings that unfurled for his ultimate, the wings being a part of his body, not just some "magic sprouting wings", it would add to Aatrox overall, the wings for his ultimate come together with wings in his base form. These are wings you cannot toggle, Aatrox's physical wings.
I know this would take more time, but I think it's worth the time! Aatrox can be excellent and his fans know this, I know they pine for the Aatrox of old but in my opinion it's better to make this one as good as possible. They will appreciate that even more.