I think changing models unless they are still a model of a weapon like native models, or loompack models is ok, because they are still a models of weapons.
bullshit like Pandor is using is cheating imo, because at this point u start to use a bright cylinders instead of arrows.
As for arrows some other models are ok, unless u have a different feathers colors etc, but still, they are arrows.
Thats a middle-ages kind game, so people shouldn't shoot with plasma...