Thanks to your toughness skill you will receive extra battle rounds: +1 at 10, +2 at 30, +3 at 60. If the opponent's toughness is not high enough, he/she will not attack in your last rounds. The cap on this skill can be increased to 100 (where you get +4 battle rounds) by the belt of toughness from the auction house.
Learning level: 16
Max level: 60