Let's see if there's something interesting in them
1) Leader evade forward
As written, the rules require leaders who survive a kill check to evade towards their side's map edge. Modify this to allow leaders to evade sideways or forward if they can move one hex and end their move on a friendly unit.
I consider this a minor technical change that has relatively little effect on overall play dynamics, but eliminates a bothersomely ahistorical edge case.
2) Optional discard
Give players the option of discarding a card from their hand in addition to playing one. When a player does this, their end-of-turn draw is two cards rather than one.
I find this eliminates the problem of getting stuck with cards you can't really use, effectively reducing your hand size. Of course, there's an argument that it subverts the designer's intentions by giving both players more tactical flexibility than they ought to have. But it still seems to lead to historically reasonable results, which suggests it's not bending the system too far out of shape.
3) Sudden-death overtime
As written, the rules dictate that a scenario ends the moment a player increases his/her banner count to the scenario's victory level. Change this to end the game at the end of the turn following the turn on which a player increases his/her banner count to the scenario's victory level. Banners taken later in that turn also count, including banners from units destroyed by battle-back. Then the opponent gets a turn to respond.
Sometimes the standard end condition leads players to do things that would be tactically very stupid in order to grab the last banner, like sending a lone unit out of line to pick off a single unit in an opposing line. By changing the end condition we discourage go-for-broke moves and keep pressure on both players to use good tactics clear through to the end.
Like (1) and (3) but I think (2) subverts one of the intentions of the game, namely recreating the "fog of battle" as the box says.
I can imagine historically how commanders would have faced frustrations such as orders not getting through, going to the wrong unit, being misinterpreted, not having time to issue them, receiving erroneous reports and units not using their iniative at the crucial moment.