1) Dueler 1) Soldier 2) Someone armed with a pistol 3) Wild Bill Hickok, notably 
A pistoleer is a soldier trained to use a pistol, or more generally anyone armed with such a weapon. The earliest kind of pistoleer was the mounted German Reiter, who came to prominence in Europe after the Battle of St. Quentin in 1557. These soldiers were equipped with a number of single-shot, muzzle-loader wheel-lock or Snaphance pistols, amongs...
• (n.) One who uses a pistol.
Pis`to·leer' noun [ Confer French pistolier .] One who uses a pistol. [ R.] Carlyle. 
[n] - someone armed with a pistol (especially a soldier so armed)
noun someone armed with a pistol (especially a soldier so armed)