If you were to create a weapon...

A hand held Death Star. Destroy planets with ease!

 

A sphere that gravitates around the character, shooting short-ranged bursts of lasers to protect him/her while they are mining?

 

A gun that shoots hyper-sonic acorns
hits enemies and plants trees

 

What about a weapon that lets you terraform and kill enemies with the earth and so forth. Lava streams, tsunamis, and earthquakes are at your disposal.

 

A Chamethrawer. A chainsaw with a flamethrower attached to it, also a symbol of freedom worldwide.

 

A flame thrower pistol (a flamethrower small enough to fit in one hand), Fire grenades (napalm grenades), Flash bang grenades, pyro mines, flame wake gun (shoots a wall of fire), and "Cerulean Sol" (a gun that launches balls of blue fire!).

 

A tentacle/vine whip that you can attach to an enemy, leaching their health for your self healing, while you attack them with another weapon. Automatically lets go when the victim dies or you get too far away.

 

A water gun... If you shoot some one with it they laugh so hard, so it makes them distracted so you can have more time to think of a better weapon.

 

If the water gun had enough pressure, it could have strong knockback. o3o It would also put out environmental fires if they existed, and damage flaming mobs.
A similar weapon could be a wind gun/fan that shoots huge gusts of winds at enemies, knocking them down/stunning them for a second and possibly disarming them ;D

 

I got one of those! :D

 

Dual wielding gun swords, the handle is a handgun and the bayonet is a katana maybe.. It's also a can opener

 

My friend says "Bear launchers." :D

 

IM FIRING MY LAZAR BEAM GUN

 

Yes! Exactly like that.

Would be pretty boss.

 

Laser halberd

 

Knifes aren't to throw, it's to stab! So, Knifes.
Knifes connected to a chain, that we can throw and push (Like Terraria flails, but Knifes will be really fast).

 

The Wave Motion gun, like in Star Blazers.
Duh.

 

I have another idea, I'd create a replica 1837 winchester, because I like old and reliable guns...

Besides, who dosen't like lever-action guns?

 

Buzzsaw shield. You can raise it as a shield but it has a secondary function where you can throw it as a weapon.

 

Something like a... a... Flash Punch!
It makes you zoom forwards quickly (a little bit of course, so you can't spam it to go really fast) and PUNCH the enemy!
And of course, some Brass Knuckles. They can boost the power of the Flash Punch.