Honestly a royal with the crafter potential would be OP. Especially during a siege could tou imagine? Having montha of provisions that don't go bad ready at a moments notice, taking over the entire logistics dept allowing his troops to move on a dime. BUILDING A FUCKING KEEP OR CASTLE ON A DIME TO FORTIFY HIS TROOPS. And none of that's factoring in enchantments. Buffing gear. Making a minefield, invincible shielding... a crafter would be TERRIFYING if it reached Miyabis level
Miyabi could conceivably hold or break siege by himself with how his abilities work.
his digging abilities lets him counter sap, his inventory can store basically limitless food and water, he can plop down whole bits of infrastructure on a whim, he's learned enough to figure out the basics of most machinery and intuitive enough to work out the rest.
Crafters may lose to specialists jobs, but Miyabi is what happens when you get someone dedicated to improving AND has hands on the entire crafting process... I wouldn't be very surprised if he ended changing the general perspective on crafters from just "inferior" to "needs training and guidance".