Reading through the history of potential recruits, you see slavers mentioned yet you never come across any. Maybe this could be added as another foe to fight. they could be caravans to attack, hunting parties (looking for peasant to enslave) or even camps. Apart from some enemy variety, it could open up some new equipment like execution hoods (cause they don’t want their identity known) or whips that could cause slashing damage or entrap like nets. Some different kinds of leather armour templates (most probably cosmetic but give early unit more variety in their looks).
Also this could give new recruit templates like escaped slaves (that could range from poor to amazing stats because you don’t know what they were before they were enslaved). You could also have slavers looks to change their occupation like killers on the run. This could create new events between slaver and a freed slave.
You could also have the opportunity to recruit a freed slave as a reward when you successfully attack a caravan or slave camp.
This could also be vehicle to introduce new ethnicities to the game (on a limited scale) if the game’s future opens up new regions/cultures.
I know this is a low magic world, however, sine we have necros, what about demonists. They can conjure demons/devils. Could create a few enemy types like imps, devils and demon warrior/lords. The demonist would be like the necro where their offense is not much but they can summon a new imp or two per turn the way the necro constantly raises the dead. This could also be used a possible end game crisis.
I think this may have been mentioned previously, however, I would like the ability to dye armour and shields. I believe dyes are already in the game as good you can buy and sell yet have no use other than loot. I think it would be a nice addition to transfer your ragtag collection of misfits into a unified and cohesive unit with uniform of sorts. We have a standard that we rally around, why couldn’t we have uniformed look to go with it.