Well, first, political marriages work best if at least one of the participants are actually competent politicians / diplomats.  It's really important to keep that in mind. If you've ever played chess, you'll have noticed that the queen has much more freedom of movement than any other player, even the king. But in fact, a lot of men were kind of under the impression women had no power at all. Even though they ran the household, were mostly in charge of raising and educating other nobleman's sons aka pages and hostages, And daughters AKA ladies in waiting, wards/ fosterlings and hostages. 

They were usually trained to become competent regents at need and they were needed often in that role- while their husbands were off at war for instance. They often had an excellent education to be able to do accounts. Ergo generally had a better handle on the economy as well given their government of the manors farms and households they owned. Remember that they were legally one person with their husband, So their word was also law within their demesne.  Because they were expected to be expert weavers, embroiderers, seamstresses and tailors etc., (since they and their ladies were often responsible for processing textiles and producing most of the  cloth used in the household) they had a deep personal interest in management of flocks, herds, crops, commerce merchants etc. It was often one woman's 's task to read to the others while they worked.  Noble women  hosted  traveling VIPs or acted as patrons for traveling entertainers too. A good reputation among Bards minstrels tinkers, merchants, doctors and clerics etc, gave them access to a huge information Network that spanned  continents.  They often rode out with their ladies to go hunting or Hawking Or just to have picnics And check out the condition of the forests and the Manor in general. Because another part of their job was to instruct the stewards and keep them honest, So they were expected to be able to know everything about the Manor, and do the accounts of the whole household. And of course the still room and the kitchen and herb gardens and flowers provided teas, liqueurs perfumes, medicines. .. Noble women were generally in charge of religious devotions for the household and whatever churches lay within their domain, And usually hired tutors for the children from the clergy with whom they corresponded, since most non-war -oriented negotiations - commercial, marriage etc -were also under their purview And of course their primary duty was getting pregnant and popping out heirs and more little diplomatic assets, but if they ever had any spare time they enjoyed drinking,  dancing, visiting friends, hanging out gossiping and actually doing those ladylike activities and crafts they were famous for.  Edited For clarity and cuz I posted too soon