Actually they are all pretty good rules when you think about it. XP
Chains/handcuffs: With these, you can accidentally clothesline people, or if one person falls, the other will as well, and could lead to some pretty bad falls down stairs. >3< I've heard of people doing that.
Shoes: With portland, it's smart to wear shoes. XD You know, broken glass, gum, and whatever gross things that probably shoulden't be mentioned on the ground. No one wants to step in any of that.
Mock fights: This can just lead to tripping and falling if the floors are marble and such, leading to a few cosplayers getting concussions or hurting a wrist or ankle. (Con stories can be scary. Oo )Plus there's the chance you could accidentally hit and hurt someone who was just walking by. I think poses are just fine, though. :3