Kharille wrote:
Wonder whether there is a roleplaying 'situation' to make it awkward to wear armour. Same way you get climate problems, maybe some environmental situation that makes it awkward. Does +3 armour need a lot of maintenance? Does it rust? Or is it naturally some kind of stainless steel?
Maybe you can create more aquatic environments, marshlands, marine adventures...
Whilst I can't comment on how enchanting steel affects how quickly it rusts, normal steel plate would start rusting very quickly and ideally needs daily maintenance - one of the reasons most knights would keep squires around to ensure the armour was regularly polished and oiled. Sweaty knights and damp air is a perfect combination to cause rust.
As for environmental factors that might affect when and whether a knight wears plate, it's worth mentioning that he certainly wouldn't be sleeping in it (although I find night-time encounters are not something you can pull off regularly as a GM without it coming across as unfair - one of the benefits of the knight profession is that the knight can wear plate, so depriving him of this advantage too often isn't going to sit right with the players).
You should also think about the Knight's code of honour - he may not be prepared to strike a woman, or a child, or something, so may hesitate in a combat against someone who is (or appears to be) a woman or child. Also, the knight may be duty-bound to accept someone's surrender, and then he's stuck with the dilemma of what to do with a potentially dangerous prisoner who will likely try to escape\kill him at every opportunity.