Replicas of a 2,500-year-old Chinese sword, the Sword of Goujian, have gone viral and are causing airport security concerns during the May Day holiday. The popular souvenir items are sparking warnings.

During mainland China’s recent May Day holiday, a 2,500-year-old sword went viral on Chinese social media – but not for the reason you might think. Lasting from May 1 to 5, the May Day holiday – also known as “Golden Week” – sees large numbers of domestic tourists flocking to popular travel destinations across China, including the Hubei Provincial Museum, which houses the famous Sword of Goujian. Many of them end up buying a replica of the sword in the souvenir shop. As a result, the main...