You're asking if they're deadly? Go have someone strike you with a pipe. I'm sure the effect would be somewhat equivalent to that. If you fight someone with brass knuckles, you may as well be fighting a robot when that punch hits.
As for fighting fair, that sort've honor is gone in this day and age. I agree that a real fight should be fair, otherwise you can't really determine who the better contender is. However, since that scenario isn't likely, you've got to prepare for anything.