I'm not a big fan of the idea. Parts of what I like about BM is that the game mechanics only takes care of the big picture. For example, you can't just send a RP that your army is bigger than the other one, or you can't RP that you've won a duel when you have not. The details, however, are left to imagination. You can roleplay that you have a shining armour if you want to. There is no need to make a game mechanic for that.
If you want to have a new type of paraphernalia to protect from wounds, however, that would all right. However, I propose that this paraphernalia be called "bodyguards" rather than "armour".
