Patlin
Explorer
MoogleEmpMog said:2 feats, +3 to-hit, average damage 19.5, crit 19-20
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Let's give two feats to the greatsword wielder to "even things out" - Weapon Focus and Power Attack.
+5 to-hit, average damage 19, crit 19-20.
Also note that with 2 more points of base attack, they could have an absolutely equal attack bonus and the power attack user is doing 3.5 damage more on average. And the power attack guy doesn't get constant questions from barmaids and evil overlords as to whether he's compensating for something!
I'd have to agree that your "power gamer" isn't particularly good at power gaming. The best way to even things out may be to help out your other players with building effective characters and using them well through some friendly advice. If the other players are taking feats like "Diplomat" and "Skill Focus(Riding)" the imbalance might be on the other end.