What would you give for a working lightsaber? Or, barring that, a pulse rifle from Aliens?
If we could make fictional weapons real, there's no limit to the ass we could kick. That's because writers and prop departments are usually pretty good at coming up with weapons too badass to exist. Usually.
Sometimes, though, they get so involved in making something that looks cool on the screen that they come up with a weapon that, in reality, would be more dangerous to the guy using it. For instance...
Why It Could Be Cool:
Because he's the goddamned Batman.
Why It Absolutely Is Not Cool:
We all know Batman loves to maintain a consistent theme. And we're fine with that. We don't mind that he calls his car the Batmobile, or his hideout the Batcave, or his computer the Batputer, because it doesn't affect his crime fighting. If he wants to have a cool bat screensaver or a bat-shaped birthday cake, whatever, as long as it works.
It was at the invention of the batarang that somebody should have intervened and told Bruce to spend less time worrying about every single accessory fitting the theme. Making your deadly boomerang thing bat-shaped makes it hard to store, hard to throw and, in reality, would be next to impossible to catch without severing three of your own fingers.
Look, Batman, the bad guys aren't going to care what your weapon looks like once it's lodged in their neck. Don't worry about it, you look fine. Quit primping, get out there and stop some goddamn criminals.
Why It Could Be Cool:
It looks pretty cool, and considering Chewbacca can do a pretty good job of tearing your head off without a weapon, you'd assume whatever he's carrying is ten times as badass as, say, whatever Han is carrying.
Why It Is Absolutely Not Cool:
According to the type of people who study the workings of completely fictional weapons, the bowcaster is like a crossbow that uses two polarizing orbs to generate a magnetic field to accelerate the little arrows.
That's right. Instead of the hundreds of other energy weapons available in the Star Wars universe, this one decides to use a technology we gave up somewhere around the time we decided that being covered in mud and shit wasn't all that cool. Sure, the bolt is covered in a sheath of something called plasmoid, but then what's the point of having a little bit of metal in the middle of it? Why not just fire the energy? Is there some super-futuristic armor in the Star Wars universe that can stop an energy beam but not an arrow?
The bowcaster also has to be cocked before each shot, which would be fine if you were fighting the Senior Citizens of the Molasses Nebula, but can be bothersome when the enemy can fire unlimited blasts of energy at the speed of light. Hell, we're pretty sure that alone makes the bowcaster shittier than the guns you can pick up in an average pawn shop.