how to balance lee sin

I'd disagree. If the decision were mine to make:

1. Stealth reveal removed. Lee Sin is a generalist, and therefore shouldn't double as a counterpick, in my opinion. This cuts off some power without taking away what makes him iconic.

2. His Q's execute damage is replaced with a substantial amount of flat damage. Part of Lee Sin is playmaking, and that's fine. However, the execute allows him to be extremely difficult to secure or steal from, because his Q essentially gives him a damage nuke to make his smite constantly superior to other junglers, save for Nunu and Cho'Gath. This is why Lee Sin can get so many steals, and is rarely stolen from.

If he'd need buffs after that, I'd give it to him. This isn't about making him weaker, I just think these are the two most annoying parts of Lee Sin that could change without ruining his design.