How to fix lethality

Okay, here's the problem with lethality as I see it. It was intended for assassins to use, but what happened is some ADCs found they were really deadly with it, particularly in the mid game where you need to win that first team fight or two.

So here's my suggestion for the effect:

Lethality (melee only)

Fixed. Now you might need to compensate some ADCs who were dependent on it afterwards if they turn out too weak without it, but that'd get the effect back to its intended use.