A  Transportation Security Administration worker inspects a traveler’s documents on Thanksgiving eve at Reagan National Airport. (Michael Reynolds/EPA)

“En garde,” you cane-carrying fliers: You may be armed, and the TSA thinks that’s dangerous.

A sword concealed in an antique walking cane was intercepted this week at a Transportation Security Administration checkpoint at Dulles International Airport. The woman carrying it told the TSA she’d bought it at an antique store and had no idea that the sword blade was hidden inside it.

“Interestingly, this is not a rare occurrence,” said TSA spokeswoman Lisa Farbstein. “TSA officers around the country detect swords and daggers concealed inside people’s canes with some frequency. Most people, as was the case with the woman traveling through [Dulles], don’t realize that their cane has something hidden inside.”

She was allowed to continue her trip, but without the cane.

Sword canes were a popular form of self-defense carried by gentlemen in the 18th and 19th centuries, when the well-to-do often needed to ward off hostile advances on the streets. Most conceal the blade so cleverly that someone shopping for a nice old cane would never know.

“People pick up these types of canes at flea markets and antique shops without realizing that there is more than meets the eye,” Farbstein said. “Some people receive them as gifts from friends or relatives who don’t realize that there is a weapon tucked inside. Some people are given the canes from family members who are passing them on from generation to generation — also typically without knowing what is hidden inside.”

She said buyers often are attracted by the knob or handle of a cane or its sturdy weight. She recommended that people with antique canes try to screw off the cane’s handle before bringing it to the airport.

Most often they are carried by elderly travelers who seem more surprised than security screeners to find blades hidden inside. One TSA report from San Antonio International Airport said a woman was shocked at the discovery of a 2-foot-long blade in her cane.

The incident reports said: “She stated that she didn’t realize that her walking cane contained a sword and that she has had it for 30 years.”