Martial arts

Combat Skill

Further increases bare-handed damage when no weapon is wielded. Can be used with weapon gauntlets.

Nothing stops you from enhancing martial arts as soon as you have enough training and free skill slots. The link to bare-handed combat is in the training instead: unarmed hits train bare-handed combat until that skill reaches Grand Master and train martial arts only after that, while kicks train martial arts at any time.

Martial arts bonuses come on top of what you get from bare-handed combat. The to-hit and damage bonuses in the table are totals with bare-handed combat at the same skill level, as the game's own skill screen shows them: each level above Unskilled gives +4 to hit and +3 damage from martial arts, and +3 to hit and +2 damage from bare-handed combat.