Change the way Tahm's empowered abilities work?

I was thinking Tahm is very strong for the role he is supposed to fulfill (A tanky/support), he is more like a bruiser than anything and one that makes melee champions inferior to his kit. So I was thinking as a way to somewhat balance him why not let it so that Tahm's passive once stacked can only use either his Q or W for the empowered ability, in where once using it, it consumes the passive stacks. Also have a cooldown for the same target to be stacked upon, (around 5 secs). It might seem harsh but I think it would put him in a more balanced position... As it is right now he is an anti fun champ to play against.