Sabers need to be made specifically for Quest or PC and are not interchangeable between the two. You can tell which platform a saber is for by the file extension. .saber files are for PC while Quest uses .qsaber or .whacker files.
The latest mod for Custom Sabers is now called Saber Factory, and can be found in the #pc-mods channel in the BSMG Discord or in Mod Assistant. Run Mod Assistant, select the Saber Factory mod, and click Install.
Custom Sabers for Quest are provided by the Qosmetics mod. The latest version can be found in the #quest-mods channel in the BSMG Discord. Sabers are called whackers and are currently hosted in the Qosmetics Community Discord. Legacy filetypes like .qsaber made for older versions can still be used. .zip files can also be used but will require you to extract only the .qsaber.
Inside the game in the main menu you will see on the left a CUSTOM SABERS or SABER FACTORY button under the Mods section. Pressing it will open up the menu you can use to select which sabers you want to use.