@JoshuaFord Considering what she thinks of him, I think she wants to be considered his equal. A diamond mind is very valuable, and by starting the bid out at 50/50 she's indirectly showing that desire to be on equal footing despite how much more it seems to benefit him. I mean, he gets a mage, land, and half a diamond mine. She gets a swordsman, half a mine that is already supposed to be hers to begin with, and the man she loves. From a purely statistical standpoint he seems to get more, but her feelings towards him likely made her unconsciously want to give him more and you could say she gets more emotionally. At the very least she could have gone the traditional route and said he'd receive 30 or 40% and then haggle up to 50, but she either figured he'd be more reasonable and be grateful that she offered half of the entire mine on top of everything else or simply didn't think about haggling up from a lower number. From his point of view he has more to gain from this deal, so honestly he should only end up with about 40% at max as the final offer.
@shinrakvsa Under traditional circumstances he'd probably get most of the rights, but this is a contract their making where they both gain something and have certain rights. Right now she's the current head of the household and isn't married, and while there is no man to run the house during such times a woman, usually the wife of the late husband, would be in charge until the heir inherits the house. Since she's the sole heir she thus inherited the land once she was of age, which occurred recently. Of course, we don't know the extent of women's rights in this particular universe so they could have more power then what we can see. There's just not enough information about the subject yet, but we'll likely find out more as this marriage contract continues to be discussed and when they finally marry.