He said Cornflake's award to Magic Matt was misleading towards the public and insulted the original Grand Master of Magic's more than 40-year history.
"It disappoints me because it undermines all the people who have gone before us that have done so much for New Zealand magic over the years - it's just about respecting our heritage.
"This is extremely disappointing."
The brotherhood has now banished Cornflake.
Mr Watson, who won the Brotherhood's Grand Master of Magic in 2006 and has been practising magic for 53 years, said he also had a problem with the fact that Cornflake's website claimed Magic Matt was multi award-winning.
"I don't think he [Magic Matt] is a legitimate magician and it's misleading the public."
However, Cornflake, who has been in magic for 11 years, said Magic Matt had come second in an IBM competition and had won the Orewa Baptist Church talent contest in 2000.
When asked whether coming second counted as "winning", Cornflake said:
"A lot of people say that someone at the Olympics won a silver medal when they mean second."
Complaints have been lodged with the Commerce Commission which claim Cornflake's award was false advertising.
Cornflake, whose real name is Justin Lane, said he would fight the accusations and refused to change the name of his award. "I gave Magic Matt the Grand Master of Magic award and it just so happens there's another award called that ... honestly, from the bottom of my heart I never intended to cause this much upset.
"For us this is more of an in-house award, like employee of the month."
The Takanini clown said he chose the name of the award because he thought the words "grand and master sounds really good" but knew the other award existed.
