The game isn't balanced in the first place, so that isn't an issue.
In fact, the game is horrendously imbalanced right now
because of the weakness of armour.
Therefore, fixing armour will actually
reduce the amount of balancing work that needs to occur in the game.
Right now, all melee attacking units are much weaker than ranged units,
especially melee attacking units without shields. Look at this, archers can easily murder infantry who outnumber them
more than 2x.
The only thing that keeps infantry relevant at all is shields, and even then you don't need many infantry at all, because a small amount of infantry forces the enemy to drop their shields, allowing your archers at the back to shoot into melee. Therefore the best party which gives the best results against any enemies is always "small amount of shield infantry supported by lots of archers", or "stacked Khan's Guard who are archers as well as being the best melee troops in the game."
The game is horribly imbalanced because armour is so weak against arrows - so fixing armour will make the game more balanced.
They will become comparatively stronger. Right now noble troop tiers are something like this:
Tier S: Khuzait Khan's Guard
Tier A: Battanian Fian
Tier C: Every other noble troop
Tier C-: Faris.
If armour is fixed, and glaive is nerfed, it will look more like this:
Tier A: Every noble troop
Tier A-: Faris.