Take akimbo pistols as Secondary.
Bonus: Extra pistol ammunition.
This does not stack with the Tactical Knife attachment; if both are used, Duelist will override the attachment and renders it useless, wasting an attachment slot.
Previously, this removed the fire cap of the semi-automatic pistols.
During the WWII Closed Beta, Duelist allowed the player to take two attachments on their pistol (as pistols could not accept attachments without this basic training), and Akimbo was an attachment that could be unlocked.