they're sold as paperweights all the time. like anything, if you use it against someone, it can be considered a "Deadly weapon."
Better to have a fist pack if you can't carry an edged weapon, which is far superior, IMO. I mean... without a blade, would you rather get hit by brass knuckles (assuming they fit you) or an elbow to the same spot? Remeber, you have to get the BKs ready, right, so why not go with a spike or solid pen instead and go that route?
In my opinion... they're a lot more of an intimidation thing vs. practical self defense use... but yeah... in your own home, you should be able to order some online no problemo.
Mustapha,have you thought about Kubotan or Jitte type keychains?I think even the non-metallics now have metal inside to set off metal detectors(Rats!) but they'll often do in a pinch for a little extra 'punch"to your fist.You might be able to find someting that suits you at 1sks.com,orrelated websites.
yes, it does cost some money but they're hefty pens, pretty badass for a gouger. Check out the tip. A guy on another forum regularly carries his into courthouses... of course, it's just a pen, but could still really do a number.
used to be called an impact karambit. Ring finger goes into the hole and the "L" shape goes on the soft fleshy part of your fist... so if you were to do a hammer strike, it would be a LOT more concentrated, do much more damage without hurting your wrist. The ring part also acts much like the brass knuckles (absorbing the blow). Just another option... and if the ring doesn't fit your finger, the polymer is easier to reduce than metal so it will fit better.