Not sure what a bard ninja could do? I have never heard of it myself. As for a bard standard is:

Music
Peace or provoke or discord
Magery
E/I
Med
and you still have 120 skill points to distribute if skill cap is 720. You can get 2 bading skills if you wish.

I have a Provoke mage in my guild and she does really well in heavy spawns w/ so many targets to provoke. You have EV's for attacking and can invis and heal. She rocked against the void shadow when everyone else was getting killed.

I have heard of a necro bard but I have never seen one before but that definitely would be interesting to play with and different.

Good luck and if you do the necro bard let me know how it goes and maybe I will try it myself.