The busy hub's North Terminal was evacuated for several hours on Saturday and Jerome Chauris, unemployed and of no fixed address, was arrested.
Bomb disposal experts were also called to the scene and carried out a controlled explosion after Chauris was allegedly seen behaving suspiciously.
According to court documents, he was carrying an MP5 calibre 4.5mm air rifle and a lock knife.
Chauris wore a white striped shirt and his black shoulder-length hair was swept back during his appearance at Crawley Magistrates' Court near London.
Thousands of passengers and airport staff were evacuated from the terminal in the incident, which came a day after a series of coordinated terror attacks in Paris in which at least 129 people died.