Some characters, like Horla and Jenkin for example, have Enlightens that change the way they play, sometimes in a way that might not be ideal for certain team compositions.
I suggest adding the ability to toggle Enlightens to a lower level, maybe with a cooldown so that people can't abuse it?
It would also allow content creators to +12 a new unit for testing purposes, but then temporarily downgrade them to help showcase the character at lower investment levels.