The handrail macro in Avance Steel can create rails of many and varied designs but unfortunately it does not yet contain functionality to automatically produce ball post or key clamp style rails. This is an outstanding feature request.
In the meantime we have provided some generic parts of these types for you to insert as required. key clamp style fittings were provided since AS2011 and ball post style items have been included with AS2012. If you watch this video it will discuss how to use these in your models.http://www.graitec.co.uk/as_webinar_on_standard_parts.wmv
Aleck Giles - Application Engineer, Graitec UK.