Hello everyone,
Sorry for this noob question, but I don’t know how to equip two pistols. I can equip only one and on right slot Off-Hand, even it says “One-Handed Ranged”, what I missed?
You must equip an item which grants pistol dual wield:
Gunslinger’s Jacket (level 20)
Gunslinger’s Talisman (level 25 recipe)
Marauders Ammo Pouch (level 26)
There are higher level upgrades of each item as well: Empowered Gunslinger’s Jacket, Empowered Marauders Ammo Pouch, Marauder’s Talisman. There are also a few legendaries which enable dualwielding for endgame characters.
If you do not have one of these items equipped you cannot dual wield pistols.
Thank’s, just crafted Gunslinger’s Talisman. And this is hard dps boost. 
Does Nightblade Dual wield work?
Are you talking about Dual Blades?
“This is a melee dual-wielding bonus. Also enables the ability to dual wield melee weapons.”
So, not unless you’re planning to pistol-whip people with your guns instead of shooting them.