I will be really short to not make you waste time:
- Aatrox appearance is too bright and plane. I would use darker reds and add textures to his chest and red arm. In his chest you could draw a more evident effect like a hole, due to his heart is on his sword
- Aatrox needs a running animation
- Passive should affect only on champions and maybe large monsters. It has a too long cd to make it too much easy to waste.
- Passive need to be more clear, more bright in the sword maybe
- Passive should slow and/or more range and/or less cd
- Q cd between every cast is too long. It feels bad. Too long to fast cast. Too short to basic attack.
- W mechanic should change because it is a really unsecure cc: skillshot and possibilty to avoid the pull
- W area should be more thematic shape, it feels strange.
- E feels bad, too short and only 2 charges. Increase at least to 3 to use with full Q
- E damage buff should have more evidence with particles
- R... I love it
- R description should say how many ms, ad and hp (when you revive) you got exactly
- Justicar Aatrox splashart doesn't fit with the new model (wings and body colour). It seem a lazy way to change the splashart. Besides, in general I would change the little wings on his head (at least the colour), right now they doesn't fit well.
- Justicar Aatrox: change heart symbol from passive hit
- Mecha Aatrox: change heart symbol from passive hit
- Sea Hunter Aatrox red arm looks weird, specially his hand. It seems a bad 3d model. Besides, I miss his ray wings but I think that is just a opinion.
- Sea Hunter Aatrox particles could be dark blue.