I specialize on stairs and handrails. I have been using the NAAMM for years and it is a good manual. Regarding the handrail portion.... there is no good reference.. NAAMM, Julius Blum, SBCCI, etc, etc. The gurus of structural engineering still do not have a reliable standard. I always develop my own model using SAP or a similar software. You will be surprised on the stress reductions and the results.
Mauricio Salazar, P.E.