Paladins have Nova, Barbarians have durability. In my games, (Champion) Fighter is going to be the reliable one, with a very simple expertise to two chosen weapon types (later a 3rd and 4th). Also, +prof to damage. Don't know if it would work for your game, just my 2CP.
I like the idea of adding +Prof to damage, though it tends to favour 1-handed weapons. Maybe alter the Fighting Style benefits, and greatweapon adds x1.5? I would prefer to replicate Barbarian nova ability (via Rage & Reckless) though, and more attacks seems the Fightery-est way to do it.