I just think straight nerfing the melee isn't the answer. It should be able to deplete all remaining health when the shield is down. You have this nice visible shield pop telling you that it's safe to melee. You don't have to continue wittling him down, until you figure that he's half-health, before you melee.

I also think it's a problem that in the case of a pure melee fight, the guy who lands the first punch always wins. He's ahead of the damage over time curve and all he has to do is keep throwing punches. I know that's a special case, but it highlights that the melee mechanic is kind of thoughtless. For being one of the "Holy Triangle", it strikes me as needing more design attention.