There are already a healthy range of weapon types in The First Descendant, but aside from just finding one that you like the feel of, you will want to pay attention to any unique abilities. Not all guns have one, but those that do are well worth equipping for the extra power they provide. As you get stronger and level up, those abilities might start to no longer do the trick against tougher enemies, but you can enhance them to kepp them relevant into the late game. Here's how to upgrade any weapon's unique ability.
How to enhance Unique Abilities
You may notice four empty squares next to any weapon with a unique ability. These are potential enhancements, but what the game isn't so clear on is where you need to go to enhance them or what you need to do it. Here's what you need to do.
Step 1: Get a weapon with a unique ability.
Step 2: Get a duplicate version of that weapon. This one does not have to be of equal rarity or have a unique ability.
Step 3: Go to the Workbench in Albion or any field camp.
Step 4: Select Enhance Unique Ability
Step 5: Select which weapon you want to enhance.
Step 6: If you have duplicates of that weapon, they will appear below. Choose the one you want to use to enhance your main weapon.
Step 7: Once selected, you will see a preview of what improvements your ability will get, and how much Gold it will cost in addition to the weapon.
Step 8: Hold the Enhance button to confirm the enhancement.
Step 9: You can repeat the process up to four times, provided you have enough duplicate weapons and Gold.
Note that you can pass on enhancements between weapons. For example, if you enhanced one weapon up to level 3, but found a stronger version of that gun, you can use that level 3 enhanced weapon to enhance the better gun to become a level 4 right away.