Spirits bard looks okay - nothing crazy cpmpared to normal bard shenanigans, and the flavor isn't bad on it's own (although I can see it being handled very poorly.)
Undead warlock doesn't impress me. I don't like the temporary form change, especially as a first level feature. That's a barbarian idea, and really tracks poorly with undeath. I'd rather see a smaller permanent change (necro resitance and advantage against fear?) and just have the shift increase as new subclass features are applied.
On top of that, Grave Touched highly favors greataxes, but mostly favors eldritch blast, because that obviously needed a boost. It should probably be once per turn.
Edit: after thinking some more, I'm not so sure about needing to nerf the damage boost. It's not better than sorlock nonsense, and should be balanced by the fact the you only get a few uses of Form of Dread anyways - unless you have short adventuring days, that is.
Plus I really want to make a half-undead barbarian/warlock dragonborn now...