More focus on non-combat solutions, I would like a questline or guild which focuses on something which doesn't necessarily require combat solution. I'm thinking a diplomatic guild/questline,
example: an aristocratic ruling is creating poor people, help the (insert group name here) get elected.
Or even a traders guild, and help grow an economic empire.
I once again suggest http://www.gamesas.com/bgsforums/index.php?s=&showtopic=1022343&view=findpost&p=14801714 as it contains different H2H fighting styles (lethal and non lethal ones too) and your combat style varying depending if you fight normal, offensive and defensive.
I like it, I had some differences in mind though, but overall it pretty parallel to what I was thinking. I imagine that you start out with just some sort of normal style, and then you're able to learn the styles if you fulfill the basic requirements.
I was actually thinking of something along the lines of combos, simply based on combination's of normal attacks and power attacks, I know a lot of people don't want combos, and that's alright, because I'm not thinking of traditional combos, but more on a system where you assign the style or combination of attacks, to a sequence of attacks that you want to press. That way, even if you've just been trained in the most lethal elite fighting style, you can just assign it to a simple (Attack, attack, attack) combination.
It could also be as you suggest, that when you choose a fighting style, all your attacks change. I definitely like your take on integrating martial arts into it.