Is the armour factory useless AKA can any units actually use it?

[Slaists]

come on alot of units can upgrade armour , its a very important building ( es when you are under a mongol's arrows shower ... ) .... and seeing them look different on the battlefield is great !!

Well, the maximum extra armor rating one can get with upgrades is +3 (I think). That's less than padded armor (4) and we know that it is very easy to kill padded armor units even with peasant archers... So, besides good looks, there is not much to be gained from armor upgrades (in terms of protection from missiles).

On a side note, it seems ridiculously easy to kill mounted units with low level archers. A couple volleys from peasant archers and mailed knights go from 40 to 30... Do not ge me wrong, I would have no problem if this happened after a volley from crossbows, but peasant archers? Come on...

And shields do not seem to be much of a protection against peasant arrows either... The only case where I saw difference was a unit of armored spearmen standing under hail of arrows from my peasant archers. Not many fell until I got another unit of peasants to flank the spearmen and shoot them in the back. After that the spearmen (armored!) died like flies... (even though the animation showed some of them in the rear of the unit raise their shields and face the flanking archers).