I guess that’s because the Model itself is set to only be scene by the owner. Check the Components Tab und the Mesh.
Search for “Owner” and you will see these two options. I guess “Only Owner” see is marked there.
The First Person Template only has Arms and the Weapon. They are set to “Only Owner” because otherwise you would see
floating arms in multiplayer.
You will need to add a new Mesh (the THIRD person one for example) with a weapon (i guess the Market Place has Animations for that).
There you leave these two check marks empty and the other Player should see the model.
http://puu.sh/fkEVR/342a877b4e.png
You can use the “Animation Starter Pack” (it’s free) from the Market Place for this second Mesh.