I think it depends on the world it is in. Rumple did say that magic is unpredictable in this world. Now I was wondering if it was all magic or certain kinds of magic. Does the state of the world we live in make it easier to power up certain types of magic? (Like true love seems to exist much more frequently in Fairytale land and has the power to break curses, poisons etc but here honestly it is fairly rare and does not have that kind of power).
Our world is a fairly bleak place with some rays of sunshine. Would that mean that dark magic has a lot more “energy” to use as a energy source?
Depending on how magic works in this world (its unpredictability, its energy source) and the precautions Rumple took (like the misspelled name on the dagger–was it a prop error or his way of using the power of the name to make it so he could not be controlled and his burying something in the forest)… I think that is going to determine how much power the dagger has.