Yeah an armour system would be interesting. Especially if it affected both damage reduction and movement speed (or attack speed or dodge distance); and you could obtain different pieces of armour for different body parts (helm/coifs, vambraces, greaves, breast plate/hauberk) from loot boxes or the emporium and mix-and-match different pieces on your career character to get a unique cosmetic appearance and modify how tanky and mobile they are. But I agree, not till Vermintide 3 (or Darktide).
maybe something like:
3 armour classes: heavy, medium, light.
Each piece of heavy/medium/light armour gives you +5%/+2.5%/0% damage reduction.
Vambraces modify attack speed : -5% for heavy, -2.5% medium, 0% light.
Greaves modify move speed: -5% heavy, -2.5% medium, 0% light.
Breast plates modify dodge distance: -15% heavy, -7.5% med, 0% light.
Helms modify something like block speed because they occlude your vision or ranged weapon range or ranged damage or recticle size.
Then instead of giving tanky classes like IB and FK damage reduction talents you give them talents that allow them to ignore or minimize the negative affects of armour, like “all negative effects of heavy armour are counted as medium and medium is counted as light”. Don’t know what you’d do about slayer and zealot - maybe a passive like " cannot wear armour but frenzied state in battle gives them the damage reduction of medium armour (+10% total) with none of the negative effects".
The range of damage reduction available would be further restricted by what types of armour drop from commedation chests for each class. For example, Shade can get a heavy helm but only medium and light armour for other body parts, whereas FK and IB chests only drop medium and heavy armour pieces.
I find it a bit odd that the GK has a full suit of armour on and gets 0% damage reduction while a ranger veteran wearing a leather jerkin and no helm can get 30% damage reduction by using exuberance.