There are plenty of places to find free and high quality assets for personal use (which modding is, as long as you’re not asking for money for your mods).
https://www.fab.com/ - great for Unreal Engine, since you can import whole packs of assets with everything already set up.
Selecting Unreal Engine in formats will show fully set up assets and packs that you can import and instantly use. Other formats will require manual setup.
This step depends heavily on what assets you're importing and the way the artist created them. Some have extremely basic material setup and come with materials, where all it takes is dragging textures into a window and some are more involved, requiring some knowledge of how materials work overall.
Sockets are used for attaching assets to each other, specify points for things like spawning particles, and so on. In weapons, sockets define where characters grip the weapon, how it’s attached when sheathed, displaying weapon trails, and establishing actual weapon length.
Open your static mesh asset.
Click on Socket Manager
If you don’t see it next to Details, you can enable it in the Window menu.
Add 4 sockets with the following names:
RightGrip - On the handle, where character holds the weapon
Carry - Where weapon will be attached when sheathed
Trail - Usually around the middle of the weapon to display the trail when swinging
weapon_tip - At the very tip of the weapon
Once the rest of the weapon is set up and usable, it’s a good practice to come back to sockets and adjust them as you test your new weapon.
Weapon template is where you define what the weapon is, which mesh it uses, and all the parameters needed to use it in-game.
Right click where you’d like to create the template and select Blueprint.
Choose MistWeaponItemTemplate from the list.
Open the new file and start filling it out.
It’s best to open an existing weapon to check what values can be kept default and what should likely be changed, and also to see which options are used across different items of the same type.
Alternatively, you can always copy an existing template and edit it.
Some important fields are:
Name
Category
Sound Category
Tier
Icon
Max Stack Size
Volume
Mesh
Activated Mesh
Sheath Mesh
Max Durability
All the damage fields
Carry Type
Phys Material
All the combat parameters
Save the template.
if you’re missing an important value, you’ll see an error message explaining what you need to do.
A broken version of the weapon will be automatically generated. Make sure to save it and resave the template.