That’s a special holster that requires a federal license (an AOW, which you need to learn what it means before possessing one), and is unlike 99% of pocket holsters that are used by most people for their pocket guns, which safely cover the trigger.
A holster that is considered a “Any other weapon”? These types of holsters (known as shoot throughs) are not classified as a weapon, and a pistol inside one of the holsters is not classified any differently.