I have an idea I think could fit very well into the next historical Total War. I propose that after each "critical" battle, where you were expected to lose by say, 30%-70% or worse odds, you can get the option to decorate a unit that survived the battle. This choice comes up after the battle screen has closed and you are presented with a selection of all the surviving units, allowing the player to choose one that they believe was the most honorable, a group of spearmen that held the line, cavalry that cut down the enemy general, artillery that sunk hordes of oncoming ships, etc. This unit then gets a small bonus to morale for being pride of the land, a small unique ornament is attached to the flag they hoist into battle or on their coats or something similar to make them physically recognizable, and the player could even possible choose a small clothing addition to customize them with. Perhaps a wolfskin scarf or a golden line on their uniform. This would add a lot more emotion to the player and this unit, as they would feel a connection to them while also understanding that they could easily die if not cared for. If the ornaments and clothing are carefully selected it can still be made to fit the historical nature of the games, and it would add to the idea that this is the players army they command into battle.
Hope you consider adding this I think it would be deeply enjoyable.