Charles held the trial run for William during a family holiday at Birkhall in Scotland last month.
The heir to the throne taught his son how to dub a new knight with a blade brought from the capital along with Prince George's pram.
Staying with the prince was also his wife Camilla and daughter-in-law Kate.
The incident is described in a Time magazine interview with the Prince who is the cover star of the latest edition of the publication.
William carried out his first investiture ceremony last week at Buckingham Palace and the training from his father was a success as the ceremony passed off apparently without any problems.
Catherine Mayer, Time editor at large, chatted to the heir to the throne and some of his friends for the article.
Describing the training session Ms Mayer wrote: "Prince William needs to master the key move of granting knighthoods, laying a blade on the shoulders of recipients, ideally without inflicting injury.
"So on Sept 26, Charles interrupts a family visit at his Scottish residence Birkhall with his son, wife Camilla, daughter-in-law Kate and the youngest Windsor, baby George, to stage a dress rehearsal, using a sword that has been dispatched to Scotland from London along with George's Silver Cross pram."
Ms Mayer also revealed that actress Emma Thompson is a passionate fan of the prince's footwork on the dance floor.
She wrote: "Dancing with him, says his old friend, actress Emma Thompson, is 'better than sex'."
The editor at large also revealed that the high profile guests that grace Charles' dinner table are known as "Bond villains" by members of his household.
Talking about the motivation for his charity and public work the prince told Ms Mayer: "I've had this extraordinary feeling, for years and years, ever since I can remember really, of wanting to heal and make things better."
He added: "I feel more than anything else it's my duty to worry about everybody and their lives in this country, to try to find a way of improving things if I possibly can."