This is a mod in two versions that lightens the sprites used in game.
I only bought this game recently, and when I tried the sprite unit option I was immediately struck by how dark the sprites were.
So, I've brightened them up a bit. Here are some screenshots that show the Prussians and Austrians -
Row 1 - In their original form
Row 2 - Lighter
Row 3 - Lighter Still
You might like to back up the following file first just in case you want to go back to the originals - ROP/Graphics/3DModels/Armies&Fleets_3D
Lighter Sprites (as shown in Row 2)
Lighter Still Sprites (as shown in Row 3)
Extract the pack of your choice into ROP/Graphics/3DModels and overwrite when asked.