As long as there's an Internet, there'll be people utterly incapable of defending themselves – especially against people saying "Buy this, it'll totally help you defend yourself!"
Belt Clip Cyclone Knife
This is the opposite of self-defense: a product which actually it more dangerous to be you, even when there's no-one around and it's turned off. If you looked at the tri-bladed thumb remover and asked "How could that possibly be safe?" the answer is "It can't" – even on its own site, 50% of the reviews is text about people cutting themselves. Even when it was closed and clipped to their belt.
If you tried to throw this ridiculous Krull-a-like with enough force to actually hurt someone when it got there, they'd still be more freaked out by how you just hurled three of your own fingers at them.
How To Build Your Own Bazooka
Paladin Press has been testing First Amendment to destruction since 1970: they once kicked a guy out for being excited enough about insane military books and he went on to found Soldier of Fortune magazine. Their very first publication was "150 Questions For a Guerrilla", proving the controversial theory that some antigubberment gun-wavers are actually literate, but they've branched out to such diverse texts as The Art Of The Rifle, Hit Man, and The Lethal Art Of Filipino Knife Fighting. And all that still looks like The Care Bears Share In Candyland compared to:
The site starts "If you get a bang out of the flash and thud of an explosion…", knowing that the invincible legal armor of "Informational Purposes Only" protects them while selling DIY demolition devices to people sexually excited by blowing stuff up. Otherwise known as "EXACTLY the people we don't let buy bazookas for extraordinarily good reasons."
Then again, it may be an honest attempt to help the gene pool. The book points out that a bazooka is "only a barrel with a few essential items fastened into place", and if you're prepared to pour explosives into a hand-cut length of pipe guided by a writer who says "psh, it's easy" (knowing they'll be at least a hundred miles away when it's fired), go right ahead. Future generations will thank you (as will this one if you get a posthumous YouTube account.)
SWAT C-8 Pepper Ball Launcher
Clearly designed for those who want to shoot people without the dagnabbit gubberment causing hassle. It looks like a gun, it feels like a gun, and the advertising website uses the word "punk" more in four paragraphs than Dirty Harry managed in five movies.
But a self-defense product shouldn't turn you into accidental target practice for law enforcement. The orange bars on toy guns aren't magic "get out of being shot free" cards, they're there to make the police check if the target is a man with a gun or a seven-year-old. And you're not seven. If an armed officer sees you waving this around like it's not lethal, which only you know, he's going to shoot you to smithereens and the wrongful shooting inquiry will award him damages for having to deal with your stupid ass.
Bob Taylor's "Power Throwing" DIY Knife Throwing DVD
If you can't see what's wrong with a trainee knife thrower practicing on his own, congratulations on getting this far into the article without killing yourself.
Most self-defense DVDs are scams to harvest money from bullying-victims who want to kick ass but are still too scared of wedgies to interact with other people, but in this case Bob Taylor genuinely won't risk being in the same room as the people he's training. Which proves that at least he knows how to defend himself.
Bob Taylor is what happens when a Napoleon complex decides that conquering Europe is for pussies. Five foot six and his bio reads like a Fight Club Fanfic, with forty years of learning "in the filthy streets ruled by drug-dealing gangs." He's a streetfighter, a bounty hunter, a dog handler, a chi master, NARC, bodyguard, knife-designer and apparently composed entirely of the "When I grow up" dreams of ten year old wrestling fans. He doesn't list his credentials in bullshit, if only because the rest of the story does it for him.
If this DVD sounds like something you want, please stand up and wave your arms so that the worried orderlies and their police backup can find you more easily. Also, tough – even since we found this DVD online it's disappeared from every online store, presumably because even sites that will happily sell you "Bob Taylor's Advanced Gun Disarmament" (which encourages people whose only experience of combat is watching it on TV to attack armed gunmen) think the knife-throwing DVD is stupidly dangerous. You'd have to coat a DVD in plutonium and Mike Tyson-attracting pheromones to make a more lethal disc.
Vending Machine Disguise
In a display of survival instincts which makes lemmings look like Rambo with a particularly large knife, Japanese women are attempting to evade muggers and rapists by
- a) not running
- b) wearing incredibly visible clothing
I could mock this idea until it was rendered obsolete by humanity evolving past "crime" and into "perfect energy beings who know nothing of violence or awesome video games," but I could never top this picture:
It was created by fashion designer Aya Tsukioka as an anti-rape/mugging dress that transforms into a vending machine with a couple moves. And sadly, it only works in theory.
How it could be improved: You're outfitting women with clothes that turn into a robotic shell, and the best you can come up with is a vending machine? Come on Japan, after thousands of hideously ill-conceived animes this is the one time a teenage girl having access to an armored robotic suit is actually justified. What on Earth are you waiting for?
The Self-Defense Pen
Unless you're writing a check to hire the A-Team you are not going to defend yourself with a pen, making this the most dangerous "get your own ass kicked" instruction manual since G.I. Joe last told toddlers to stand up to bullies. CNC Machined Heat Treated Stainless Steel might be the ultimate in ass-kicking when it's striding through flames as part of the Terminator, but when it's a website-educated wannabe waving a writing implement at muggers his only chance is if they're laughing too hard to punch him properly.
The "pen as armament" worked exactly once, and that was in a movie, and even then it's cheating because Schwarzenegger only uses weapons when he runs out of one-liners about his immense fists. Add the fact that someone whose starts with "weapon" and gets to "pen" is unlikely to shove it in either of the two locations it would actually work, because that would be icky, and you've got the worst weapon since the double-ended sniper rifle.
Samurai 3000 Ninja Sword
This is where weaponmakers stopped even pretending self-defense was involved. They're just selling solidified fan-fiction. The "Samurai 3000 Ninja Sword" sold by SelfDefenseProducts.com not only mocks its own name by smashing the words together like that, but is obviously built to look like a lightsaber, and even its own description talks of "plasmium swords" before almost embarrassedly admitting it's made of stainless steel.
Every single one of these blades will occupy pride of place over an entire collected run of Neon Genesis Evangelion, single handedly disproving psychic powers and the Force. Because the owner will infuse it with years of heroic revenge fantasies, standing ready to defend the honor of creepy resin catgirl figures/that cute girl at Subway, and they'll still hyperventilate and slice their own thumb off if they ever try to use it.