Luke should have said that while everybody thought he was just wasting time and idling, earning the nickname Orc Prince, he was, in fact, learning all sorts of things in secret. Things that actually were of interest to him. It would still be poor behavior for a prince, but at least it would be better than to be forever known as a waste of skin orc. As it is, he has already served food fitting the palate of a princess, is in the process of curing a disease considered lethal, played the piano as a pro, fought bandits and assassins remarkably, etc. It seems like the first prince is also putting one and one together as well. The king ought to be shocked to hear the report when the first prince returns home.