Presumably, taking into account the northern location, frontier feel and deep wilderness of the country, it was some sort of accommodation of the economic realities involved in establishing settlements. Presumably, Angaraks lacking the Christian family values that got American families to pull together in similar situations, they needed some sort of legal recognition of the quid pro quo of supporting/protecting/not-raping the women who came along. Combined with things like dowry and all the rest of it, they probably evolved this system that was like a business partnership, but applied to a domestic arrangement. It's like having a permanent housekeeper whom you have to provide for, protect and keep (the knife-fighting thing is not much more effective than slapping at deterring a serious rapist or mugger, given that men in such eras were more likely to carry weapons and have experience with sword, spear or arrow wounds) in sexy clothes, and I guess you get the profits from her dancing or other occupation in exchange. Given the disparity in social graces and decorum exhibited between the typical Nadrak male & female, this might have been a good system for allowing them to get to know each other at close range without compromising her marital potential.

Or more likely, Eddings thought it would be a nifty twist on slavery without thinking the whys and wherewithal completely through. I like coming up with explanations for aberrant stuff though.

Well, that's weird by our standards, but given their cultural issues and values, they all seem to make sense.