The Devil’s Disciple (Irish Repertory Theatre, 132 W. 22, extended through Feb. 10). My favorite off-Broadway company has just extended the run of its incisive small-scale production of George Bernard Shaw’s 1897 play, a sneaky piece of theatrical prestidigitation in which the shell of an old-fashioned Victorian melodrama is stuffed with decidedly un-Victorian notions about morality. Tony Walton’s staging is brisk and unpreachy, and the cast responds to his lightness of touch with acting to match (TT).