I just lost my level 8 Sorcerer and I'm going to make a Warrior Muse/Marshall Bard.
You have access to Dirge of Doom that has a 30 ft range, meaning it wants you close to the front line. (effectively grants +1 AC/+1 ATK to everybody)
Dread Marshall Instance gives weapon dice damage. (+2 DMG to everyone using a weapon in a 10 ft emanation).
Bless gives +1 attack to everybody.
Marshall makes you and allies adjacent to you immune to flank.
At level 10 o I'm going to give my party.
+2 DMG on weapon attacks
+2 Attack
+1 AC
Immunity to flank
I'm going to be in melee with a Guisarme (reach and trip) doing AOO and Triping foes.
I still have my spellcasting to use Blood Vendetta, Invisibility, Fly, Dimension Door, Soothe, etc.
It surely isn't the "best optimized build ever" for but I don't think it's bad. Let's see if I don't regret it.