This is a tutorial about how to give one armor the same model as another armor but different textures. In this example, I'm showing part of the process I used to make my Phantom Knight mod, which makes some parts of the Phantom Armor look like the Soldier's Armor, but using different textures. The textures are from Kyim's Royal Soldier mod.
Nvidia Texture Tools Exporter
This mod contains many Switch icons which you can extract with Toolbox. Just extract the bnp with 7-zip and look in the content/UI/StockItem folder to find the icon files.
This page will help you find the filenames for the armors you want to edit.