I actually thought that Callum wanted to become a mage because he's, well, a nerd. He was never gonna get good at physical skills like sword-fighting and horseback riding, but because magic was super intellectual and abstract thinking, he could actually be great at it.
I’m always amused (and not in a bad way) that people think Callum’s issue with training to be a prince was that he was lacking in the athletics department, and thus couldn’t live up to the expectations of a physically gifted warrior.
Which ignores the fact that Callum himself mentions how bad he is at the intellectual, abstract stuff as well.
Callum: Look...Rayla. Princes are supposed to be good at things. Swordfighting, leadership, riding horses. But I’ve always been kind of bad at, well, everything.
Callum: Growing up, I was supposed to learn horseback riding, swordfighting, archery, battle tactics, but I was so bad at everything.
And in the book, we have:
“Now Callum had obligations. Responsibilities. Being a prince meant horseback riding, training with swords, strategic thinking, and learning the history of Katolis. Callum had struggled with all these subjects.”
And Callum goes into detail as to how bad he is at just memorizing the names of old battles. My point is, Callum wasn’t just struggling with physical activities, but with the so-called intellectual/abstract stuff as well.
I’m not trying to be obtuse here, but the kind of person a prince--or really, any member of the royal family--is supposed to be involves some combination of brains and brawn. Harrow, Sarai, and Amaya were/are all great warriors. But Amaya is also “known across the land for her brilliant battlefield strategy and improvisation.” Sarai was Harrow’s closest advisor. And Harrow himself was clearly wiser than most of those around him.
Callum might be bad at all of this at the beginning of s1, but as the story progresses, we actually see him improve in most of these areas.
He starts to come up with battle tactics.
We see his strategic thinking elsewhere in the story.
He also shows signs of being a competent leader. Like, consider this: Rayla, Claudia, and Soren are all deadly opponents fighting each other, and then they basically stop because Callum told them to.
Callum: Listen. It’s late. Let’s all just get some rest and cool off. If, in the morning, I can’t convince you that we’re all on the same side here, you can fight each other then. Agreed?
He improves at horseback riding, no easy task while riding a Moonstrider.
The only areas we haven’t really seen Callum improve in are archery and sword fighting. But when you can use a sword to scale an incredibly tall tree, using one to fight doesn’t seem so challenging!
Callum will continue to explore magic; there’s no question about that. But there’s also nothing preventing him from also becoming a prince. And it’s looking as though he might get good at those princely skills too!