I think his q should be the baseline for his other abilities. The only time I ever saw an Aatrox was with devourer, and even then he'd have to farm to get stacks instead of fighting. W feels weak, and the toggle takes almost a 10th of your hp per proc. E is basically just waveclear and an aa reset, could do so much more with this.
I feel like aatrox should have a large zone of control wile his ult is running or when his blood well is full. His other abilies should be able to benfit the team, and provide engage.
Here's a my take on what his kit should look like.
Passive: Cd lower at level 11 and 16
Q: same as is but jump can't be interrupted wile in rage or if blood well is full.
W: Need to think about something to do with his sword, need ideas.
E: Torment slash, 20,25,30,35,40 hp per cast (?)
Cd: 14/12/11.5/10/8.5
Aatrox uses the untapped emotions of those around him to channel energy into his sword.
Aatrox can store up to three charges of torment and can expend one charge at a time to deal damage in a long v-shaped skillshot (think rumble e but bigger. Each blade hit slows for 20/23/25/30/33% ( doesn't stack) (same range indicator, but wider zone of effect)
R: Rage of the forsaken, No cost. CD: ??? Duration: ??? Damage: 250/350/400
Aatrox is empowered by the battle of his allies, and screams of his foes.
Each time one of his allies hp goes below 33% within 1500 units, aatrox gains increased attack speed and lifesteal (stacks up to 4 times). His auto attack range is doubled wile rage of the forsaken is active. (can only happen once per champion, per life, so sorry soraka)
When Rage of the forsaken ends, aatrox unleashes all of the bound fury within his sword to deal a massive aoe blast in a circle around him. Enemies hit are feared for 1 second as they lose the last of their sanity.
I really like Aatrox as a champion, but his kit really falls flat, I've tried to make him work so many times.