For the warriors trait, I'd probably split it between Accuracy and Attack, since they'd be more familiar (accuracy) and also probably stronger. I imagine a lot of practice would make you stronger as well.
Just a thought.
My original idea was for an increased attack, but when reading the description of the corresponding trait (training), it made me realize that Accuracy was more important. I thought about having a +1 Initiative also, but looking over the faction tech traits, I noticed each one gave one additional advantage (Scholars, for example gave a +10% research while Adepts gave 40 extra mana); so I decided on increased Accuracy for the Warriors trait to reflect a faction's familiarity with weaponry.
As for attack, I was thinking of a new trait: Might (+10% Attack); this would be for factions whose people are physically stronger.