Something is wrong with the combat promotions. It is gamebreaking.
Combat I and II work as planned. but with Combat III you have less bonus than with II (don't remember exact amount), same with IV. At Combat V you have a "bonus" of -70% and at Combat VI the "bonus" is -125%. Also, you get 10% less healing in neutral lands instead of a positive amount. I tried to edit the units in world builder, but when I started removing promos the unit got even worse, like having -360% Strength and stuff.
This needs to be fixed as it totally ruins the game!
Otherwise a great many improvements since I last played a month ago. I read the thread about the new Combat System and I am thrilled about it! (Maybe this is causing the problems, by the way? Just a thought...)
Edit: I use the most recent svn (updated like two hours ago as I write this).