The 31-year-old man, who had previously been under house arrest in France, was held upon arrival in Fez on Sunday, where authorities discovered the items, as well as a black balaclava, in his luggage.
He was not challenged as he checked in with low-cost airline Ryanair from Nantes in western France, despite heightened security following an Islamic State group attack on Paris in November that left 130 people dead.
Local government officials identified him as convert Manuel Broustail, a former soldier who was expelled from the army in 2014 following a report that he had been radicalized during a mission in Djibouti.
He then became the leader of a group of radicalized Muslims in the city of Angers, also in western France, even organising "paramilitary-style training exercises", including one that took place just days before the November attacks, according to French intelligence.
He was arrested in November after the attacks and placed under house arrest.
The municipality of the Loire-Atlantique region said Broustail was no longer under house arrest when he checked in for the flight, and there was no reason to stop him leaving France.
According to photos published in Moroccan media, Broustail's luggage appeared to contain at least four kitchen knives, a machete, two pocket knives, a truncheon, a balaclava and gas bottle.
Another photo showed Broustail, with a bald head and long, bushy beard.
The municipality said France had signalled the man's presence to the Moroccan authorities and that his arrest in Fez "was not a matter of chance".
The Dublin-based carrier Ryanair told AFP the case was "the responsibility of Nantes airport security officials who are investigating".
The municipality said his hand luggage had contained nothing out of the ordinary, and his checked baggage had not raised alarm bells when passing through electronic detectors as it did not contain explosives.