When Bruce Lee was handed his first pair of nunchucks in the mid-1960s, he called the weapon a “piece of junk,” his training partner, Dan Inosanto, recalled recently.

Mr. Lee, the martial arts expert, said the nunchucks were not as effective as sticks — too fancy and too showy.

“Then he goes, ‘This might be good for the movies,’” Mr. Inosanto said in an interview.

It was a good bet. Wielding nunchucks with dizzying force, Mr. Lee vaulted to international fame. Americans flocked to martial arts.

But the popularity of nunchucks — commonly, two rods connected by a chain or rope — alarmed the authorities, in what many now see as a hysteria that echoed other racist fears of Asians. The police began arresting people for carrying what some called “deadly weapons.” In four states, lawmakers banned them.