Right now, there are 3 different ranged weapons in the template:
Melee weapons are not implemented yet, but the structure of the classes should allow you to implement it easily.
Please follow this part of documentation How do I create a new Item?
Remember to select “Spawn Instance”, to be able to select the weapon class.
Keep selecting item tool options and create your weapon assets.
At this point, you should already be able to equip your weapon. However, keep reading to learn how to customize its animations.
Create a new Animation Blueprint, that will be used as overlay layer when the weapon is equipped, make sure it derives from ABP_RangedWeapon.

Configure your animations following these section Animations
Link your Anim BP in the Equipment Definition of the weapon, it starts with ED_ prefix (e.g.: ED_Shotgun)

You will already find an Anim BP set as overlay instance, but that’s just a default value.
Now you should be able to equip your weapon, either from a Pickup Actor or using Starting Items (see Starting Items)