I don't want any unique weapons such as the Glaive from Krull or the Darksaber from Star Wars, instead I want a type of weapon where there's more than one. This is obviously more of a sci fi thing since most fantasy weapons are just a real world weapon with magic applied to it or a very stylized design but there could be fantasy examples.

My first pick that comes to mind is a sci fi one, though. It's the flechette guns from the Honor Harrington universe. What I like about weapons in this universe is that they feel like what our modern weapons really might evolve into. The flechette guns are standard sidearms, like the equivalent of a pistol. Like most Honorverse guns it uses magnetism instead of chemical combustion to launch projectiles which makes them travel much faster and hit a lot harder. It fires a cone of tiny metal darts (flechettes) which are almost guaranteed to kill the target at close range. There's a great scene where a guy pulls his flechette gun on some guys who are standing right next to him and catches them by surprise. These are superhuman soldiers wearing body armor and the flechettes turn them into red mist, basically.

And that's just the standard sidearm in that universe intended for close range combat, their pulse rifles are much more powerful, so powerful that if it hits your left arm from far away the entire left side of your body is probably destroyed. The best part is that all these weapons are pretty much what the guns of the future will probably look like. I'd take a pulse rifle over a Star Wars blaster rifle any day.

The humble Lasgun,

often mockingly called 'Flashlights' by fans of the series they come from, Warhammer 40k, its truly a misplaced name. The term 'Flashlight' comes because compared to the standard weaponry of the other races, its extremely weak, however, it is an amazing gun. Its power is also not to be scoffed at despite being so weak compared to the weaponry of other races in the series as even laspistols can punch straight through concrete walls and floors and still have enough energy to kill the person behind it and they don't 'burn clean holes' through you [well, given the sheer amount of lore in 40k, it really depends, but by and large] what they do instead is cause all the moisture in the hit area to evaporate and expand causing the area to burst like an overripe tomato. Very gruesome, very effective.

The Lasgun comes in different shapes and variants including some that have different firing selections and power settings. But more then their power, its their stupid reliability that makes them such amazing weaponry for infantry. You can have lasguns that are ancient, and I mean ancient, as in thousands of years old, and they will still work just fine. When worlds are becoming daemon worlds [which means the laws of physics are starting to no longer apply as the new owner makes the entire planet pink because they enjoy that color] lasguns are one of the very last things to stop working. But it isn't just the gun, the power-packs used by them are awesome. You can charge them on anything that gives off electricity [with differing levels of efficiency] and even throw them into a camp fire and they will recharge [although it loses efficiency and increases chance of malfunction]. On a plus, if you are desperate, you can cause the powerpack to overload and use it as a makeshift grenade.

The Lasgun, it may be called a flashlight, but it blows a lot of standard issue sci-fi weaponry out of the water.

The Sky Hook from BioShock, that thing can saw people in half but I never hear it mentioned in debates involving it's main user.

Yautja blades the Predators use.