also, characters who can willingly do it are Sanosuke, Saito and Aoshi.
other character's up on D pad do different things. (Kenshin sheaths his sword for Battoujutsu stance, Yahiko enters a counter attack stance, Shishio sets his sword on fire for extra damage) --- if you don't know what Shadows of the Damned is. get on it. http://www.gametrailers.com/video/preview-shadows-of/714488