Please don't make Aatrox into Rhaast with a sword.
What the title says. I like Aatrox as being a calm, collected, war-god kind of entity. He's always been the leadership kind of guy when it comes to his VO and his old lore, I get that you're trying to fit him to his new lore as being "me kill because darkin", but I feel like that's really kicking Aatrox players where it hurts.
I love the slow/heavy style you're aiming for since it'll be less of a "Q into the team then afk-auto" style, but Aatrox's current VO nature is perfect. I get that the current Voice Actor probably isn't in-touch, and so that you'll have to change the voice by a bit, but as long as it stays in the same general direction, that'll be nice.
As for his model, I really do enjoy his thin build as it adds some level of unnaturalness to him, seeing how his build doesn't fit his weapon really hammers in that supernatural demonic feeling. I just really don't want to see black and red Alistar but with wings and a sword
, because that's what that current sword design makes me feel like what's going to happen.