Hello there, I have checked you model and I am not sure whether these things cause the problem, but I think it's better to point them out.
- The LOD for player meshes should be 100 I believe.
- The dislocation of the arm maybe caused by lacking of empties, so here is what I am taking about.
Add an empty named it shape.
Add an empty named it detail100.
Parent detail100 to shape
Parent all armatures to the detail100 as well as other meshes which has no bone.
*even though some ppl think empties are not necessary, I will still recommend you to have empties. Just to be safe! - select all meshes and hit Ctrl+A then Scale and Rotation to obData
If all these do not work. Then what I will do is delete the arm armature and redo it.
Hope that helps.