Remove the Musicianship skill, and let both chance of success, and effect, depend on skill in Peacemaking, Provocation, and Discordance respectively.
OR
Keep Musicianship skill, and remove Peacemaking, Provocation, and Discordance. Musicianship would be the only bard skill. Bards would carry a song book, and choose which effect in the same way that, say, a paladin chooses Enemy of One from the chivalry book instead of Divine Fury.
Y' all played "Tales of the Unknown Volume 1: The Bard's Tale" where effect depended on song played?
Yup, this is something someone should 'a' told the designer(s) back in 1995-1997 and I know it ain' gonna happen now.
Edit:
I wish for wieldable musical instruments. Imagine a tambourine being a throwing weapon using slightly different cyclone art, or a bassoon being a macing weapon using slightly different blackstaff art.
I wish for more woodwinds such as a "shawm."
I wish for portable xylophone-esque instruments such as a marching band glockenspiel.