I appreciate your input. But that's just wordplay. If you are looking for some objective definition of "too powerful," then you're welcome to it.
If everyone makes the same choice, thus making it such that choice is meaningless, then that is "too powerful." Use whatever heuristic you want to use. In an alternate dimension of everyone choosing Friends (or Witchbolt, or whatever) then yes, that spell is too powerful. Since we don't live in that dimension, we don't have to worry about it.
I don't want to dissuade you from having fun. If someone said, "I have this great finesse weapon that is one-handed and does 2d6 damage," I would say that it is OP in comparison to the current design goals of D&D. But maybe they have a good reason for its inclusion (such as wanting more powerful martials) or maybe they just like it. Not my circus, not my monkeys.
I thin that this type of spell will be unbalancing, but there are worse things in life.