While Playing Go to pause Menu then open the Inventory, here you will see the main attributes which is the DPS, Health, and the Skill Power. You can carry three different types of weapon in the game which can be Primary (Rifles), Secondary and the Sidearm(Pistols). Every category is capable of customization and you start up with the basic Grips.

For Primary Weapon, you have three customization slots, The First is the Magazine Upgrade, an Under Barrel upgrade and lastly the Muzzle upgrade. As you keep progressing and unlocking you can customize your weapons and make it more stable and good range. Coming to the armor, it has the same mechanics as the Weapons so do have a check on the attributes. Lastly, the backpacks which can also help you with extra bonuses like skill cool down reduction or skill power. The High-End weapons with perks will have more effect. Note: Perks are not Attachments.