Monks gain the ability to strike foes with both hands. This skill allows
a monk to attack a foe with his non-primary hand. The attack does slightly
less damage than their normal attacks, of course, but monks of high skill
levels are capable of doing a vast amount of damage with even this somewhat
weakened attack. The chance of the offhand hit going through is proportional
to the monk's ability in this skill.
Note that this is cumulative with second hit, giving a monk three attacks per round. Second hit does not apply to an offhand attack. Note also that, despite a monk's skill level, this will not gain an extra attack with a hand that is already in use - such as holding a shield or using a weapon with both hands.