[RPG] Can a character wear armour that he’s not proficient in

armordnd-4eproficiency

I'm starting a new 4e campaign and I was helping one of the guys in my group, Marc, with his CS (he's new to the game and this is his first character). We got up to choosing his magic items (we're starting at level 3) and Marc, playing a ranger, suggested +1 Razor armour (which only works for scale armour). Aside from the proficiency issue it would be perfect for his character. Up until now, in the various games I've played in, I don't think anyone in my group has used any armour that they were not proficient in and I realized today that I don't actually know what the ramifications of not being proficient in armour is.

Basically, I have three questions:

  1. Can a character wear and use armour that he is not proficient in?
  2. If so, is he in any way disadvantaged by it?
  3. If not, what's even the point of armour proficiency?

And yes, I am well aware that I can just homebrew my way out of it by saying "Well, scale armour isn't the only kind of armour with the razor enchantment; leather armour has it as well", but because this is a question about the underlying rules and not something this specifically circumstantial it will undoubtedly have future applications for me.

Best Answer

Player's Handbook, page 212

If you wear armor you're not proficient with, it makes you clumsy and uncoordinated: You take a -2 penalty to attack rolls and to your Reflex defense.