Akimbo

[Gregory]

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

[Mark Zuckerberg]

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.

[Zipporah Schumaker]

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.

[Agnes]

a [belligerent] stance with arms slightly bent and elbows facing outward. A predominant form of [posturing] meant to intimidate and add size to ones 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.

[Oralee]

[Spread out], [open wide].

[Cami]

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] thats flailing in the wind. Sunglasses are okay too.

[Magaret]

To [cross]/place your [arms] on your [hips].

[Agnes]

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

[Gregory]

When ones legs are [spread] [wide open]. Same as spread [eagle].

[Julene]

With hands on the hips and elbows turned outwards.

[Tanya Shivari]

If a persons arms are akimbo, they are bent at the elbows (= the middle part of the arms where they bend) with the hands on the hips: