1.To dual wield any firearm or other projectile weapon. Can be done with pistols,submachineguns,laser weapons,crossbows, sawn-off shotguns,and,if you try hard enough,pump or lever action shotguns,light and heavy machineguns,rocket launchers and Gatling guns.

2.(pussie definition)To spread out limbs,sticks,breasts etc.

limbs bent; most often, the hands on the hips with elbows bent outward:

To hold and fire two guns, one in each hand. Most often seen with handguns, or compact sub-machine guns.

This is not only the correct term, but also the original, and oldest term for this.

However, Dual-Fisting is the term (created by the Halo community) that
is the most popular and widely accepted.

To dual-wield(gun in each hand) firearms. Most common with handguns and Submachine guns but not limited to.
P.S. Dual-wield is more proper than dual-fist. Dual-fist has its own fucked-up description.

a belligerent stance with arms slightly bent and elbows facing outward. A predominant form of posturing meant to intimidate and add size to one's physical structure. A common technique often seen in the employ of meathead or Guido assholes as they size each other up at the gym or the club.

To hold two guns of any size and fire alternating to kill shit faster

to hold 2 pistols, one in each hand. A common image is arms extended, face focused and scrunched, blazing off wildly, NOT shooting both pistols at the same time but alternating each time. Also the shooter can wear a trench coat that's flailing in the wind. Sunglasses are okay too.