What would happen if Aatrox and Riven switched ult concepts

Riven: Riven's blade surges with power and extends, granted bonus attack range. Riven also surges with power and gains bonus attack speed. Rivens Q ability will slow on the first two strikes after the ult is active (only on the first too, since she is losing an execute she gains a small amount of sticking power that is very limited)

Aatrox: Aatrox metamorphasises into the perfect war machine gaining bonus ad and cleave on auto attacks (like Titanic hydra but with his big sword and he only gets life steal off of the main target or a significantly reduced lifesteal on xtra targets). Aatrox can reactivate to launch a blood barage that does physical dmg + missing health dmg. if the projectile kills an enemy aatrox regains a % of his missing health(or it could reset his passive giving him a second revive but that would be op?)

Why do this?

well its kinda a nerf to riven, the attack speed helps he get her passive off but she loses her huge execute which nerfs her killing power

as for aatrox his ult doesnt really work, you already build attk spd but you are forced to building tank aswell so you have no dmg or ad. this ult will give aatrox some killing power and team fight pressence that he needs. Im not a game designer so this could be broken for both, but i like experiments.

do you think this is a bad idea or a neat one and why?