well each part has different color and textures. If I make it one mesh part it’s all the same color. I usually just color and texture them in studio but I didn’t like the metal texture in studio so now I’m attempting to color in blender and just export the completed model as one mesh instead of 5.
you need to change it back the way it was when it was making it 1 texture and then editing the other images ontop of the texture and fitting all of the swords sides into the texture as you cannot use multiple textures.
You need to make a single texture for the whole sword.
Have you taken a look into UV Unwrapping? It allows you to color each individual face of your sword, which should allow you to have multiple colors on your sword, although you’d have to convert the sword into 1 model for that.
Also, if you wish to use PBR, I’d suggest looking into Surface Appearance.
the problem has already kinda been solved but the metalic property in blender doesnt work in studio and you can use roblox materials on blender models try looking into surface apearence its the link that @SwitchedDreams sent in his response
for the texture thing its best to have your blender model as 1 part like you did when you joined it if you were just using the basecolor property in blender it wont work and is much better to use uv maps
anyways kinda the same thing everyone said but hope this helps