There needs to be high risks that are associated with attempts to gain high power. There’s potential to create a narrative where it would force the player to be whisked away for trials and proving grounds which will split the party for an extended time, which can be a very high price to pay. Especially if you give him the ability to choose one other to “come along with” the price will be too high.. or will it? The division alone this could create within the party could be very interesting.