The reason it doesn't come up on tool tip is because its a PROC from the main story (defined in NPC_Stats). It is also not what you are looking for, it helps with thievery and concept of value to a character.
To answer your question about changing path influence: I don't know of any way to change a specific character stats, if you are driven I bet you could replace the player with another player with the appropriate stats but that requires ALOT of extra work (moving items, experience, etc...). It would most likely have significant side effects as well.
This is probably be a wild goose chase but you might be able to change something with ExtraProperties or Flags of items/potions.
