The Attack Score is the score used to determine any melee or ranged attack's chance to hit a target. The Attack Score is made up of a base number determined by user class plus half of the Strength Modifier (Strength-10) and half of the Dexterity Modifier (Dexterity - 10).
This means that the formula looks like:
Attack Score = user class score + (Dexterity-10)/2 + (Strength-10)/2
 2H Warriors
2H Warriors should focus on building Attack Score through Strength. Strength increases both Attack Score and damage dealt to targets. Keep in mind that several warrior skills require minimum levels of Dexterity.