Vertical progression of player stats/equipment and Open world rpg...oil and water.
It never works and no amount of added features will fix this fundamental incompatibility.
This is one of the worst effects that MMO's and isometric arpgs ( like Diablo) had on single player rpgs. It creates enormous hyperinflation of base attributes that gets more and more and more out of control everytime you gain a "level", until they add global level scaling to "fix" the issue.
It also creates comical dissonance between narrative and the world...boars in Hearts of Stone are more dangerous than Eredin and his army.
I've wrote on this before.
Create distinct weapon categories , so that each is more advantageous in certain situation ( speed, armor penetration, precision, reach, ammo availability, etc),
Divide weapons in each type into three basic "tiers": standard ( average stats, high modability), high grade ( better stats, low modability) and Prototypes (highest stats/no modability).
Use weapon load out system, so choosing right equipment for the job is important choice. Weapon and armor mods, should add extra features to the item, instead of 2/3/X times more damage/reduction.
The game doesn't really need xyz types of pistols. Simply make each type distinct and more useful, depending on situation.