FrogReaver
As long as i get to be the frog
Fighter also gets +2 damage with one-handed weapons, or +almost 2 with greatswords, which is equal to the rage bonus in the beginning. I also think the rage damage resistance is typically countered by the use of reckless attack, though reckless attack then boosts damage.
It should be possible to balance them.
Yea. That said Barbarian 1 / Fighter X is a pretty impressive build.