You don't need bones when editing meshes, or the meshes don't need to be rigged. Only weight paint is needed. There are import fixes for Blender, and the dae-conversion is no longer needed. (Blender 1.76 is easiest, 2.8 still messes up normals, but that's only concern for skin meshes really) Allways delete all LOD's but the lod0 and rename all materials to material0 (instead of material0.001) We have multiple asset modders in https://discord.gg/8RSvSMQ if you want a better channel to ask for help.