Clint_L
Legend
I think of nova damage as single huge hits, like stacking everything onto a critical the way paladins do. As you specifically cited punching through concentration checks, I assumed that was sort of what you were going for here.I'm not sure how you think it lets Paladins nova harder.
You only hit once instead of twice, and thus can only smite once instead of twice. That's less nova. (Also, Paladins need a bit of a nerf either way).
And I can't see a reason to leave rangers out, if they really want to invest in the Str to do it, might as well let them.
Which is why I think paladins would seldom use this ability even if they had it, as it would reduce their chance to get a critical hit.
Leaving it as a weapon property would let any class that can use heavy weapons and get multiple attacks use it, which is fine if that's your intent - it's your idea.