What if instead of full on reviving, Aatrox gained a shield equal to % of Well + % Bonus AD?
Brief stasis, maybe like .25 seconds
Something like 100% of well + 100% Bonus AD for 8 seconds
He sorta died, but the well formed as a shield protecting him from actually dying. He doesn't get his full health bar back but he has enough to keep fighting. This allows Aatrox to stay thematic while simultaneously giving Riot the ability to buff a lot of other aspects of his kit that they couldn't before because a 4000 health tank would just come back later if you killed him.
This also goes rather well with his W heal mechanic of tripling the heal when below 50% health.
Wanna give him better base stats? You can now. Wanna give him a better Ultimate? You can now. Wanna improve his Q and allow it to be so easy to cancel? You can now. ETC.,
You could also easily increase his AD ratios, base stats and the like across the board with this change alone. You could also lower the Revive CD, give more AS to the Well bonuses, reduce rate or timer of decay etc., **Why? Because Aatrox can actually be killed now. **
Inspired by

is quite effective now as a stuck-in sustain bruiser; just enough resistances to stay alive, a bit of health, and then all damage to keep rolling.
, which is why everyone is building him tank + bork.