You’d need to use overlays:
Here’s a thread where you can search for overlays: 📝 Ultimate List of Backgrounds and Overlays Editors / Creators!
And here’s a thread where you can learn about using overlays: A Guide to Using & Animating OVERLAYS
You can also find some overlays at Pixabay and Pexels, free of use ^^
I know that
has some.
If you got to her backgrounds and overlays, click on Smartii Overlays, then click on Weapons related and you should be able to find some cool ones ^^