Give Kayle's E an extra auto with each skill point
So instead of making her next single auto attack ranged, have it make her next 1/2/3/4/5 autos ranged (and at level 6 onward have an AoE effect)
This would smooth a lot of her issues where even when she reaches her late game she can't catch up the deficit her horrid early caused. It also opens up some potential unique playstyles, like putting 2 points into it early in a Klepto build then putting the other points of it on the backburners.