@sketches the arch duke said it takes 2 days by ship so if they are using sail ships still say 5-8 knots per hour while a powered ship can easily do 30 knots so with the time to travel by cart back to theirs then the port it was probably pretty reasonable since 48 hours times 5 knots an hour makes the crossing about 450km
Olivia already secured an other source of the mineral, so she can leave with ain if he isn't happy. Duke roundhart probably didn't thought she would be able to leave him, since olivia is a dryad and dryads in this setting seem to be unable to leave the person they have first sex with (since dryads are said to bring a good harvest you can probably think what that means for the past)
@Niemand : she can not leave is not an excuse for the treatment. Unless there is a reason her country and not invade and conquer your territory you do not treat a foreign princess as a servant or her child as the lesser unwanted son for ANY reason. A skill you prefer is one thing, but the kind matters so much more at the level of higher nobility, and heck for a high ranking moble immunity to poison, and being able to remove poison from others is a better skill to have. Since direct combat is something they should be avoiding, and most assassinations would be through poison, not ambush.
@sjmcc13 This seems to be a feudal society, where high-ranking nobles act more as generals. They get land/taxes, but have to field and lead their personal armies if the king demands it. Your other points are correct.
@botodopo I'm guessing it would be the RL equivalent of giving someone a giant perfect blue diamond, which would translate to "I like you enough to give you this expensive thing that costs as much as a city, have my babies."
@cor3zone : and how many medieval nobles lead from the front lines, as opposed to those who led from the rear and issued orders? I know there were some who fought, in the best armor available to them often on horseback, but leading and inspiring the troops is more important than being in the front, and if the troops are better served by someone in the rear keeping an eye on everything.