Chi Strike
From LSWiki
Perform Chi Strike General-Use Combat Maneuver Usage: perform chi strike [at <target>] Requirement to Use: have at least 500 points among 100% of martial arts skill, 100% of philosophy skill, 100% of pneumaturgy skill, 100% of evocation skill, 100% of bellerophrasty skill, 50% of discipline skill, and 50% of unarmed combat skill and be familiar with chi strike Typical Activity Cost: 20
Focusing your chi into a weapon, you strike with your hand in a fashion that destroys the target's spiritual body as well as the physical.
Learned by first meeting the requirement to use, and then asking to be taught by Musashi as an Aisenshi or by Rindol after completing his relevant task.