Cavalier: Add +1/2 to the cavalier's bonus to damage against targets of his challenge.Would access to this be worth a feat, especially for a huntmaster cavalier? Aasimars have a similar, but weaker, favored class bonus, but gain access to the Celestial Servant feat.
I don't know either. I think it might mean 1/2 of a point of damage? I would hope it's not 1/2 of his challenge ability as a whole. I don't under stand the FCB for dwarfs. The dr for a companion just seems way better.
Look at it this way:
Weapon specialization is +2 on damage with a single weapon.
Toughness basically equates to +1hp/HD (your favored class bonus)
So for one feat you can get +1/2 damage/level to targets of your challenge which you are going to be using more and more often as you level up anyhow. Using the dudemeister's example that's +5 damage per hit on one enemy 4 times/day as a swift action, sounds pretty good to me. Multiplies on a crit (or a charge) as well.
You have to consider that challenge is a limited times per day ability so it isn't really a straight plus x to damage. In order to get more out of it you should go for order of the flame or scoop up chain challenge come level 7.
Challenge Damage also improves with the number of attacks you make. So this encourages TWF, natural weapons or a huntsmaster gang. The Bird companion has a talon talon bite routine from the get go so that's pretty nifty.
As any good cheese the Dwarfs Cavalier FCB will need time to ripe but by the mid levels the payoff is prolly worth it if you build accordingly.
Also why not straight Dwarf? They don't get a STR bonus but there defense Bonuses are very useful for a Cavalier.