I have a handy selection of FICTIONAL Firearms and even melee weapons floating about:
Super Shotgun
Game: Doom series
Weapon Class: Double Barreled Shotgun
Pictured above is the Doom 2016 Super Shotgun
One of the most iconic weapons in Doom aside from the Chainsaw and the BFG. The Super Shotgun in all of the Doom games have always displayed an amazing amount of power. That one big blast to simply tear through enemies may not sound the fanciest, but it gets the job done as quickly and as efficiently possible.
The Super Shotgun has always fascinated me as a weapon in its respective lore. Despite looking like an old fashioned coach or sawed off shotgun, it manages to be miles above the power level among most of the other basic weapons the Doomguy can wield, while being MUCH SAFER to use than a Rocket Launcher, WHILE STILL delivering as much damage, or in some cases even moreso.
While the Super Shotgun has been in all of the Doom games aside from the very first game, I specifically mention here the Doom 2016 weapon. The main reason why I say this one Super Shotgun in particular is that aside from being an absolutely badass looking firearm, this particular weapon in said game is able to keep the legacy of its old ancestors while fixing some of the problems its old brethren had such as the overly large spread. This particular boomstick also has an upgrade that allows it to fire at one barrel at a time instead of the usual 2 before "reloading", but while that may sound like a downgrade, each shot is able to deal the
SAME amounts of damage while also increasing how fast the Doomguy re-chambers the weapon. This effectively QUADRUPLES the overall damage output of the weapon, making it one of the most powerful weapons in the single player campaign. The challenge in acquiring the upgrade for the Super Shotty can be quite challenging especially when playing in Ultraviolence Difficulty but its so damn worth it that missing out on that particular upgrade can be saddening.
Vladof Droogs
Game(s): Borderlands 2 and Borderlands: The Presequel
Weapon Class: Sniper Rifle
Pictured above is the Lyuda, a legendary variant of the Droog weapon class.
Droogs are Vladof Sniper Rifles in Borderlands 2 that have the Vladof Barrel. A signature trait of the Vladof weapons manufacturer in the Borderlands series are high rates of fire, and the Vladof Droogs are a testament to such. Basically, you combine the range and damage output of a sniper rifle AND the high rate of fire associated with the Vladof business model and you got yourself a weapon that will keep those bandits, skags, and even those Hyperion PMCs out of your way.
Gameplay wise, Vladof Droogs are very powerful. As mentioned before, Vladof Droogs are a holy fusion of your typical sniper rifle but with the automatic capabilities of an assault rifle. This means that you have the best of both worlds in range, damage, and fire rate to annihilate enemies from a long range.
Heck, Droogs are so good even when hip fired that I've made these some of my go-to automatic weapons for Salvador since he is able to mitigate the Droog's main weakness in ammo consumption thanks to his action skill "Gunzerking" which other than giving Salvador Dual Wielding, health regenration, damage resistance, and fire rate, it also allows him to regenerate ammo, allowing Sal to dish out continious amounts of damage.
Oh and Dual Wielding TWO Droogs is one of the most badass things you can do in Borderlands 2. Dual Wielding two Lyudas is basically badass x12.
Junkyard Dog Mrk II.
Game: Guilty Gear XrD
Weapon class: Hybrid Sword + Flamethrower + Lighter (yes it is a lighter)
Sol Badguy's particular weapon. There is something about a weapon that combines a sword, a flamethrower and a personal lighter all at the same time. Its glorious.