Random idea I had. So you know how you can currently invest in some business's currently? What about having more avenues for doing so? For example starting up an iron mine that would give you scrap iron passively. Or a lumber camp that would provide Lumber automatically without having to buy it. (Obviously expensive/late game but would cut down on needing to break down merchandise constantly for building weapons/armor)
Making Crafting a trainable skill would be a nice quality of life skill too....Maybe even at the university as part of a Life Skills / Craftsmanship program
Last one. Maybe Being able to invest in the Dojo for those wanting to be a gentle dom towards slaves...... becoming a patron for them or other businesses.