I'm gonna try and give them a description that would appear in the Doom manual (brackets stuff will contain basic stats and wouldn't be in the manual if real).
Super Fist: Long blades, coming out of your knuckles. Sort of remind you of a deadly Wolverine, for some reason.
(Double damage punches)
Super Chainsaw: A chainsaw was designed to go through wood. This is design to cut through the toughest metals. Nuff said.
(It will kill but not gib zombies and imps on touch, apply the same ratio of damage increase for other monsters).
Super Pistol: Slower rate of fire, but each shot would threaten to destroy Doomguys wrist, so imagine what it'll do to the poor imp it hits. (Just more powerful, 1 shot weak monsters, but SSG rate of fire)
Super Chaingun: Hey what happened? We pulled the trigger on this for 1 shot, but nothing happend but a big bang, a big jump and us losing all our ammo. Oh and that Barron of Hells body is missing it's head but still standing....... Ohhh. This is gonna be expensive, but fun.
(It's so fast it'll be hard to track each bullet, but not as fast as the description\discharge gun from sky may be)
Super Rocket Launcher: Man, rocket jumps use to be fun, but this is now stupidly dangerous. That Cyberdemon is gonna be jealous of this MFOAB launcher.
(x2.5 damage increase, and wider splash radious, MFOAB Stands for Mother F**ker Of All Bombs)
Super Plasma Rifle: Awww man, this thing has rubbish range. But within it is almost as deadly as a BFG9000. Ohh and no charge up for it either.
(Not great range, say it will go as far as a small corridor but useless for outdoors long range stuff, but will gib weak monsters and take care of medium monsters, within a second)
BFG 18000: Double the number, double the power? Don't be stupid. Science decided it would rather cube things instead so it's tripled the power. It's a Fire and Forget weapon, mostly because the room you fired it in will be painted in demon blood red but you may as well drop the weapon after firing it as you'll be out of ammo for it too. High pitched "Worth it"!
(The Cubed thing is based off the fact that if you want to make a half scaled modle of an object, you don't just take the weight of the original and half it, you half it again. Stupidly Over Powered, but requires 300 cells to fire 1 shot. High pitched "Worth it".)