It is a lyre shaped crossbow (after transformation) that fires magic "singing arrows/bolts" that enfeeble and debuff the enemy.

Remember that in XI it was crossbow bolts that enfeebled enemies whereas arrows mostly increased accuracy (although some did elemental damage). Archer "Job" could still be Ranger which grants you crossbow enfeeb abilities and if so, you would need to switch weapons easily and quickly.

Or else it's a BowHarp. I'm ok either way.

I just hope I dance a little jig if/when I sing.