I'm actually kind of excited for a new 3 Kingdoms game because it gives a chance to refine the gameplay.
I love the duels, especially when they happen at dramatic moments (I'm all about that DRAMA when it comes to Total War), but I usually don't get to enjoy them particularly because I have to be taking care of the rest of my army. I'd love a feature where you can challenge the enemy champion before the battle starts, and if they accept, you fight it out one on one. (The victor's army gets a morale boost or whatever (or in extreme circumstances, and if agreed upon by both armies, the duel could decide the whole battle).
Either that or fighting could halt temporarily so they can duke it out.
I'm not saying this should be every duel, just special ones.
My only other problem with the duels is you usually know who's going to win before hand which takes away a lot of the drama.
I think some more ambiguity before hand, and possibly some ways of changing the flow of the duel part way through? (other than using your splash damage ability.
I don't know if this is the right place to post suggestions but feel like some kind of change like this could be cool.