Even recent kings have this grand education from the best of the best if not from actual geniuses, examples abound like Alexander the great and Aristotle, and usually there’s other examples in wikipedia articles for most recent kings, even without tutoring here’s a list of books that could have been used to educate royalty in less ancient times than this case but of course maybe a book wont teach craftsmanship https://en.m.wikipedia.org/wiki/Mirrors_for_princes

The elite/aristocracy of these old ages was at the top for reasons that make some sort of sense even though it could be violent it would be perhaps not completely uncorrelated with ability, if a prince is born into it they’d sometimes get taught multiple languages, music, poetry, on top of the reasonable politics and warfare, strategy etc. As for craftsmanship that is a good question since it’s working with ones hands but with the examples here so far it would make sense if they could just get instructed by the best craftsmen as well to learn that too of course this is maybe too far backwards and another continent to extrapolate