Upon using 2 weapons at the same time (Dual Wield) and upgrading this skill, your defense is gradually increased by a percentage for each skill point added. Only the Fighter class supports this ability. If you don't like your Fighter to move slow due to having been equipped with a Tower Shield, this is another choice for being tanky and do some formidable damage as well.
1/3 : Increase defense by 4% when dual wielding.
2/3 : Increase defense by 8% when dual wielding.
3/3 : Increase defense by 12% when dual wielding.