Alright, here is what I was thinking (don't be mean if someone already had this idea):
Alright the bard would obviously use a guitar or something for the weapon, but not as like the big, sword that they have already.Maybe like a STR and magic class(don't know intelligence acronym), There could be two types of weapons, A guitar or like a lute/mandolin type weapon. The Guitar type Bard would be more of a STR type thing and use the guitar for close range attacks, not like bashing a monster over the head but like strumming/playing the guitar and having a small area of attack like thing, but they would still need intelligence and such. The lute/mandolin player would have a higher intell(What I shall call it) and there attack will be strumming the guitar but having the notes sort of, shoot of at the enemy, the difference of attack wouldn't from Guitar to lute/mandolin be big at the start, but gets bigger as you progress. Alright, The guitarist would branch off to Rocker then to Shooting star. and then the Lute/mandolinist would branch off to Note shooter then to Magic music (The names suck, I know I struggled with them) here would be the skills:
Guitarist
Finale-Maxlvl 15- Effect:The user boosts there attack speed, and power
Shooting star-Mxlvl 20 -Effect: The user send out large wave of notes
Lute/mandolin
Note explosion-Mxlvl 20 -Effect: The player sends a explosive note
Note boost-mxlvl 15 -Effect: Boosts the attack speed
(The idea is there, just not founded well)