What is better for arthritis and nerve damage, cold laser therapy or seeing a physcial therapist?

Both can have roles. There can be a place for both therapies. Physical therapy is always good for arthritis because motion will help you not get stiff. The important thing is to do the therapy and exercises at home even if you are not at the rehab center. Cold laser can be useful when battling other "non traditional" infections and toxins that can lead to neuropathies and pain.
See below. It is usually a physical therapist who is trained in cold laser technique. In general there is no one treatment that is better than another and treatment often involves multiple techniques and must be custom designed for the individual. One size does not fit all.