The incident happened when an axe penetrated the man’s helmet at the event at Hawkesbury Showground in Clarendon in western Sydney.
David Wheeldon, Media and Communications Manager for Careflight said the man suffered a heavy blow with lacerations to the head.
"A genuine axe had gone through the helmet he was wearing. These had been forged quite professionally, it's an organised group, a national event, there were people coming from across Australia to take part in the medieval style event."
CareFlight’s rapid response rescue helicopter was sent to the incident at around 11am on Saturday where a critical care team assisted NSW Ambulance paramedics.
A specialist doctor and critical care paramedics then flew him to Westmead Hospital after being judged to be in a stable condition.
Mr Wheeldon said a situation like this hadn't happened before to his knowledge.
"Doctors remarked that he may have been very lucky not to have suffered serious injuries in that incident," he said.
