When I played my first battle with fourth age total war: dominion of men the first thing that I noticed was that the shadows are incorrect and that there are sometimes two suns in the sky. The best way to fixing this is to add alpha channels to the skyboxes, make all cloudless areas + the sun transparent. When that is done you'll need to adjust cloud, sky and sun colors. I would also recommend to replace the sun texture by a more eye candy one. I've done this all before for the Rome Total Realism project and I could do this for fourth age total war too if you want me to do that.