First seen the most of was in the world war (but co existed before that and the original creator to this day hides only behind thoeries). Brass knuckles were first welded on to a combat / assassin knife handle. Later on it became it's own seperate individual piece of weapon without a knife, so it's said.
They have been used over the last century for hand to hand combat in the war, for defense and attack, to torture (as some come with spikes and studs that date back to the early 20s). And in to this day and age used by gang members, and other troubled individuals. Or often used for self defense by certain people who think that's something smart to do.
Real brass knuckles aren't the kind you see lying around today that are made of alloy and other cheap metals, often referred to as "second rate metal knuckles", but real brass knuckles are made of solid brass and weigh anywhere from 10 oz and up and are harder to find and get now a day's and have a price tag to usually match that.
Real brass knuckles have costed lives with one hit. Brass knuckles are highly against the law usually resulting in a class a or b misdemeanor, which means 6 months to a year in county jail if just caught with them, plus a fine. But it depends on the enforcer. Few get off with warning's. If you strike somebody with brass knuckles or intend to, it is assault with a deadly weapon, or attempted murder, both felonies.
Brass knuckles have proven to be highly deadly weapons if in the wrong hands as some come in a variety of shapes and sizes and are usually as painfull as they look to get struck by one. They may break or shatter bones. Though often second rate metal knuckles are generally less powerful than there brass predocessor unless they are heavy (7.0 oz or more) and / or big (fat boy knuckles), needless to say.
Extreme sharp spiked knuckles second rate or not may cause a brutal bodily injury leaving somebody without much of a face if used repatively by the attacker.
Brass knuckles are often referred to as paper weights now a day's to avoid legal issues.
Second rate knuckles can be found in your nearest self defense online store.
Very hard plastic knuckles with bumpers can also bring a punch but are less so affective than there metal predocessors, needless to say. They to are also illegal in most places now a day's. They too can injure your fingers.
Carrying brass knuckles is a bad idea, an alternative to keeping a gun at home may be brass knuckles however, or SAP gloves, which are gloves that law enforcers use for there larger or drugged out suspects. They have metal BBs sewed and weaved into the knuckles and are made of punishing leather and are often more concealable than brass knuckles. They to can bust open faces.
There is also bottle opener knuckles, which can open bottles forreals hence the name, and require two fingers instead of 4 and are half the weight and size of regular metal knuckle, I have yet to see these in brass. They have "teeth" at the top of the knuckle. And can be fairly labeled as "compact jaw breakers".
Brass Knuckles are one of the most effective melee weapons ever made. They can end fights in 1 punch. Theres other types of knuckles, like Spiked Ones, which are very dangerous, and shatter bone, AND tear skin. Theres also a trench knife, which is commonly used in the US in WW2. Trench knives are short knives with brass knuckles as handles.
In Japan they call them Tekko with a slightlly different design.
A very strong weapon, now-a-days made with high-impact plastics, or alloys. They are second and third rate brass knuckles. A true pair of brass knuckles is made purely of brass, and is going to be very expensive. It is a crime to carry around a pair of brass knuckles, they can easily shatter bones, tear skin, maim or kill someone. So, in essence, carrying around a gun or a knife is just as bad as carrying around a pair or two of those things.
Sadly however, this weapon is becoming a trendy fad. Today's Emo or Hardcore generation is wearing this mass marketed picture of a brass knuckle on every T-Shirt, Necklace, Hoody, Pair of Pants, Ring, Shoe, etc. available, and of course, the world is just soaking this up. The market is flooded with the image, because every cool kid in 8th grade has one!
So, out of ignorance, a deadly weapon is becoming trendy. Just as bad as those stupid Che shirts that every 12 year old communist is wearing, because they just know everything about politics!
Warning: There is a differrence between regular fighting and extreme brute-force fighting. Brass knuckles should ONLY be used in extreme brute-force fighting!
Brett: Dude, I got two pairs of brass knuckles. I put both of them on and totally unleashed upon him!
Billy: DAMN! I bet that really fucked him up!
Brett: I wouldn't be surprised if he was dead by now!