In my opinion, the king's right to be worried about the younger sister's influence. Instead of hitting the training grounds, the nobility has a duty to hit the books and govern their territories. Not that I'm saying they can't learn to protect themselves. Also about the comment where the ladies aren't buying jewelry or whatnot, I think the king means that with the ladies buying goods, they can circulate currency within the kingdom. Jewelry and other beauty items are either consumable or created to never be enough, so the money will always travel through the pockets of the kingdom. When the ladies decide to focus on training, they purchase less consumable items like armor and swords that are made to last. And since they're noble ladies, I doubt many of them actually really use their weapons in serious fights so those swords will probably last them their entire life without needing to be replaced. All in all, I'm thinking way too much into this and buying first-world stuff can actually help your economy stay float sometimes.