You don't necessarily need to have a material assigned to your mesh in Blender, though it helps if you want to check the material and make adjustments. (For example, assigning a hair texture to hair to see if the painted strands appear stretched or warped.) You can go into the material section and delete all of those diffuse textures. To add them back in, here's how, and please note that the screenshot is from Blender 3.3:
Next to the little icons for solid shading, rendered, wireframe, etc., there's a little arrow. Click on that and a new window will pop up that will let you turn on backface culling. This way, if the normals are facing the wrong direction you can easily see it. You can also select material or texture in this window. One of those will usually show the mesh in grey if you select it. In your green mesh, you had "attribute" selected and I believe it was showing the vertex paint.
Your mesh has a lot of problems, I'm sorry to say — there are unmerged vertices creating weird sharp edges, and overlapping faces. It looks as if it's been decimated. Don't use a decimated mesh for your LOD 0. Decimate will
destroy your topology. If you have a mesh that hasn't been decimated start with that. If not, the mesh will need work to get it in shape.
Always put your mesh in object mode and solid shading (so that no texture is showing) and pan around your mesh. Look for sharp edges where you don't want them and weird shadows. The sharp edges are from disconnected vertices. The shadows can be caused by vertices that need to be split or by overlapping faces (among other things).
Here's a quick(ish) checklist:
1. Delete the body. In the UV editor, enable sync, face-select mode, hover your mouse over a UV island, press L, then X to delete. Never join the body to the mesh until your mesh is in good shape and has weight paint, vertex paint, and a uv_1. Join the body right before assigning cut numbers. Afterward, import everything into Studio and test the mesh in the game to make sure it animates correctly. Make your other LODs
only after you're satisfied that your mesh functions as it should.
2. Select the bow via the UV editor, press P, and separate it. Remove doubles using M > by distance.
3. Clean up the main mesh. Remove doubles, merge vertices that remove doubles missed, and delete any overlapping faces. Adjust the edges to make the topology as even as possible. Dissolve some edges if necessary (X > dissolve edges).
4. Delete the right sleeve altogether. Select the left arm and parts of the shoulder, upper back, and upper chest (use your best judgment on what to select), separate with P, and then use the mirror modifier to make a new sleeve on the opposite side. Re-join the separated sleeve with the rest of the mesh. Select the entire mesh (A) then remove doubles (M > by distance).
5. After rejoining the meshes and removing doubles, you'll likely need to merge other vertices that removing doubles didn't catch.
6. Rejoin the bow with the main mesh (ctrl + J).
7. Close the holes by selecting an edge, E, S, move your mouse inward, M > at center. Select the middle vertex and move it inside the mesh somewhat.
8. Select the edges that have weird shading and need sharp edges. Edge > mark sharp. The edges will turn blue. Here's where they should be marked:
9. Your UV islands are really choppy and they will cause unwanted sharp edges within your mesh (Studio splits meshes where the edges of your UV islands are). You'll need to mark the seams and re-unwrap your mesh.
For what it's worth, I have a tutorial in my signature but please note that it's not exhaustive and it's outdated. I'm in the process of updating it but it's taking me a while. The reason I mention my tutorial is that I've tried to make it step-by-step so that nothing is missed. I also have tutorials
here and
here that cover a lot of what you need. They are outdated too but many of the methods are the same.
