Observation:
1. Deleting the battle.sd file fixes the white patches error
2. Deleting the battle.sd reverts the game back to the vanilla version of the file
3. The vanilla version does not have the hero abilities (graphics allocation) - most noticeable in Aragon's case
Solution:
I took the kingdoms versions of the battle.sd file and added all hero abilities. The xml version is also included for future editing.
Installation:
Extract the files from the attachment and place them in the ...\Medieval II Total War\mods\Third_Age\data\ui folder.
Savegame Compatibilty:
I installed the fix while exploring Fangorn and had no problem to load a previous save.
Screenshot for the ability on stand by and when triggered