hmm a lot of nuetral emotions/values are a lot more like ideas.
So perhaps they could blend in or be sort of ghost like.
One of the strongest of these would be something like balance. Who like most of these spirits. Instead of having combat prowess use nasty tricks to influence the world.
Like for example.if it was balance.They'd be like a innocent child/ typically seen eating a apple and thinking about something(child ghost in appearance.) who would make all fights between a single person or another fair. By evening out there abilities.so much so that it will end in a draw a compromise, or them both dyin at the same time.
This technique is not without flaws, but that makes them particularly hard to kill since they would make you never want to fight her by making you have the desire to fight of her own. It actually may end up just being a philosophical debate about what is fair, or something like that.
"It's only tight two willing to chage to there death at each other do so."
She'd be one of the stronger principles in the world, and if she didn't question what is balance exactly so often she'd have caused a lot of hell for both sides.