This is the knowing your true name trope, applied to one's personal demons. This is related psychologically, I believe, to Labeling Theory, where giving something a label helps limit and make it seem controllable/understandable. People use labels all the time, often badly, to reduce ideas and people into something that can be reacted to with flight/fight and accept/reject lizard logic. Why not use it for our own benefit to reduce those internal demons in a similar way so they are less scary?
That said, the true name of a personal demon means that you really understand yourself and have done the inner work to figure out what it means. Otherwise you are playing with fire.