1 - More weapon variety. Have different types of axes, swords, etc., maybe more exclusive weapons to some classes, like the Double Bow to make them unique.
2 - More classes, maybe having a special "class" skill that is exclusive to the class, always equipped when the character is in said class.
3 - Some characters being able to leave your army, turn against you, and more enemies turning to your side.
4 - As a lot of people said, alternate routes, or endings.
5 - Better maps, more varied objectives. I want them to create completely new objectives too, to keep the game fresh.
6 - Siege tomes and Ballistas.
7 - Have the eastern warriors animations be different from the western ones. Anything that can make them seem different from each other.
8 - Completely new skills, and nothing like "+2 defense" or "+4 speed"
9 - Big maps, but maybe with an option to move more than one unit at the same time while keeping formation.
10 - Finally, better and challenging map design overall.