Is it realistic to have a bladed weapon that operates sort of like a double ended light saber? As in you press a button or lever in the center of the hilt and blades come out of either end? Furthermore, could you see a bladed weapon fight club as something that may exist (it doesn't have to be legal and definitely probably wouldn't be)
On the first part? Not really.
You’ll see collapsing knives that are designed for push button deployment, out the front of the grip. But, for a full sword? No, or at least not with modern technology. Wear and abuse from normal use would quickly wreck the mechanical components. To say nothing of the blood and gore getting forced into the mechanism when you collapsed it after use.
So, again, limited to modern technology, it would be theoretically possible, but they’d have an incredibly short lifespan (maybe only single use), and be extremely annoying to clean and care for (if not outright impossible).
If you’re talking about some kind of hypothetical future tech, then, it will probably be an option some day. Self cleaning tolerances, and a mechanical stability that can’t be achieved with modern materials may make this viable. Though, at that point, this would probably be more of a novelty than a practical combat tool.
Double bladed weapons do exist. Well, I should say, double bladed knives exist, I have one somewhere. It’s awkward, difficult to hold, and I’ve still got a scar on my index finger from the first time I picked it up. These are a novelty. You buy one because you think it looks cool, not because you intend to use it.
There are a few examples of weapons that are designed to be double ended, mostly polearms, which would sometimes include functional spikes on the reverse end. It’s also not unheard of for a sword to have a sharpened, spiked pommel. That said, mounting an entire reverse blade onto a sword is something you’d usually only seriously consider if you’re either a Sith or Klingon.
On the second part, about fight clubs, “No, never; except they did.”
The basic idea of a fight club where people who don’t know what they’re doing wander in and start beating the ever living snot out of one another? Yeah, that can happen. I’ve actually been out on a farm in the middle of the night, dueling friends with plastic bokken because it seemed like fun at the time. It’s not exactly what you’ve got in mind, but that’s possible.
Thing is, there’s a huge difference between dueling with a high impact plastic katana, where screwing up means you’ve got new bruise on your knuckles, and screwing around with a live blade, where a mistake means critical injuries and death.
Organized, underground dueling also has some real world history. The only examples I’ve run across came out of 19th century military academies. I assume the reasoning is roughly the same as why I was on that Indiana farmyard in the middle of the night, it seemed like fun at the time.
Of course, in the case of military academies, we’re talking about students who’d actually been trained to use their blades, so it’s not exactly a fight club. Still stupid and dangerous, but they (kind of) knew what they were doing.
So, my first impulse on this subject is wrong. I’d say, “no one can possibly be that stupid,” except of course, I have been exactly that stupid. I also knew a couple idiots that decided to fight each other with a fire axe and cheap katana in their living room, without ever considering that, maybe, this was a horrifically bad idea. Tragically, they both survived unharmed.
As for a full on fight club? Not so much. When you have people who don’t know what they’re doing throwing punches, the potential risk of injury is, somewhat, limited. Untrained combatants are not a huge threat to one another. They can get some good shots in, and can make it hurt, but actually messing someone else up requires concepts like power generation and a vague idea of where to connect. Without them, it’s just guys flailing impotently at each other.
Blades are inherently dangerous. You don’t need to know how to put together an effective defense, or understand how to generate force, driving four pounds of steel into some poor schmuck doesn’t require training. Training does help; it teaches you how to put up a defense, and how to circumvent your opponent’s, but it’s not necessary for accidental death and dismemberment.
The fundamental problem with a bladed fight club is that the participants need to survive. They need to be in a condition where they can fight again next week. Getting carved up by a stray blow will put a damper on that. To say nothing of a stray death.
In Fight Club, the titular club was an expression of violent catharsis. For random guys who’ve never experienced real violence, it was an escape that presented the illusion of danger, without putting the participants in actual jeopardy. This kept the attrition rate fairly low, and allowed the group to grow. For something like this, that is absolutely critical.
If you start arming the participants, it would only take watching one guy getting opened up, and spraying blood all over the place before you might think, “maybe this wasn’t such a good idea.” When you start hemorrhaging members like this, it becomes impossible to keep the numbers up, and the club would die off quickly; figuratively or literally.