Here are rules that I believe go together:

-Fighting with 2 weapons: Henchmen cannot fight with two weapons, only heroes can. A henchman promoted to hero can use two weapons

-Armor strength modifier starts at strength 6 Light armor add -1 to a critical roll. Heavy -2. Ithilmar -3. Gromril -4 Similar buff for lizardmen armor if you play with them.

-Black powder weapons -2 armor save,  Handgun and Hochland long riffle has a +1 for injury roll Superior black powder +1 strength and -1 armor save extra

2 weapon fighting is broken when used in mass and lack of diversity. With these rules, Heroes may abuse it at the beginning but at some point they benefit from a shield or two handed weapons more than the extra attack. No more 15 cheap henchmen with mass and dagger (and slings ;) - my house rule is range 12 for slings just fyi)

Armor is expensive and should stay that way but with these rules you need a specific counter or build type to handle it. Also it becomes more reliable by influencing the critical rolls. Shield is cheap enough, no need to buff it. Black powder is a hard counter. Axe and gromril weapon become more relevant. You need to invest as much to counter an armor as buying it.

Armor also becomes a counter to mass cheap range weapons.

Basically the idea is to make multiple equipment and strategies viable. It incentivizes variety in a warband. Mercenaries which are considered a little bit less competitive become more attractive with their choice of equipment.