For me the game is about 'command and control' rather than the micromanaging of individual units. So you could use the cards to simulate inspired (or uninspired) commanders doing something clever (or not) and to give some variance to what are quite generic and vanilla troop types when it comes down to it.
The use of the 'Hellequin' card is a great illustration, could be done, might have been done, at least if contemporary illustrations are to be believed, but offer that as a force option and every unit will be able to do it... wargamers are like that. Putting it as a chance card is an ideal solution!
Likewise stakes, we assume that all of the English had the option of using them, which we might incorporate into their general ability, rather than creating 'stake' rules. By using fate cards we can incorporate the possibility of an individual unit commander 'getting it wrong' or doing something inspired, which increases/decreases their effectiveness for some reason.
There are a number of permutations or possibilities for the use of the cards, so that they take away the 'gods-eye view' and the multitude of choices available to the wargamer and instead force him to concentrate on a general battle plan, his deployment and hoping that his subordinates don't f**** up. We are in a period where accident of birth and not ability is generally the predictor of high command after all.