I recently made a new fighter and she is lvl 4 now.. I was thinking to take 2 levels of barbarian and 2 levels of rogue, so by lvl 14 she would be a lvl 10/2/2 fighter/barbarian/rogue... I like having those extra feats from barbarian and rogue like the damage reduction, rage, sneak attack.... Would I take a big hit in killing ability as compared to a pure lvl 14 fighter?