I have a Graves E nerf/buff idea

E: dashes in target direction and reloads 1 bullet. For 4 seconds he gains 40/60/80/100/120 armor and magic resist but CANNOT extend the duration by staying in combat. Each auto attack bullet reduces the cooldown by 0.5 seconds.

Nerf to his drawn out fights but a buff to a quick skirmish.

Thoughts? The armor and mr is what it would be if he fully stacked his E on live at each level.