Any knife having a blade that opens automatically by hand pressure applied to a button, spring, or other device in or attached to the handle, known as a flick-knife or flick gun, is prohibited.
The maximum penalty for importing prohibited goods is six months prison or a fine up to $10,000.
Cox's illegal activities came to Customs' attention on December 17 when a package addressed to him containing six knuckle-dusters was intercepted at Auckland International Airport mail centre.
An analysis of Cox's selling history on Trade Me established that on a number of occasions he had sold knives that were offensive weapons under the Act. Customs officers searched Cox's Papamoa Beach Rd home and seized 25 knives also deemed to be prohibited offensive weapons.
Cox ordered the goods to sell to friends to make some money, and advertised some knives on Trade Me after he had made legal checks on the internet.
Cox's lawyer, Genevieve Denize, told Judge Russell Callander last week that her client had no history of this type of offending and had no interest in bringing the items into the country for unlawful purposes.
As a solo father, he had intended to use the money he made to pay for his daughter's study and made about $2000 before costs, including the $600 to $700 he paid for the items seized.
"It hasn't turned out to be the money-making venture he had envisaged."
Angus Senior, lawyer for Customs, said a call to Customs or the police would have resolved Cox's query whether the items were legal or not in short order.
"The only real purpose for the knuckle dusters is to inflict violence on others and that is why it is not surprising that it is illegal to put them out on the open market," he said.
Judge Callander said given Cox's lack of history of this kind, a substantial fine or community work was the appropriate sanction on this occasion, and fined him $1000 plus $132.89 court costs.
Outside court a spokesperson for NZ Customs said the department regularly deals with offensive weapons imports.
However, because of the commercial nature of the shipment by Cox and the type of offensive weapons involved, a decision was made to prosecute him and it may be the first case of its kind.
Anyone unsure about whether articles are prohibited or restricted from importation should contact Customs on 0800 428 786) or refer to website www.customs.govt.nz.