In most jurisdictions around the world, it is legal to buy a sword. However, there may be restrictions or regulations depending on the specific location and type of sword.

• In the United States, you can legally buy a sword in most places with no specific restrictions. There may be some limitations on the size or type of the sword, and there can also be restrictions on displaying or carrying the sword in public.
• In the United Kingdom, you can buy certain types of swords. However, UK law restricts the sale of swords with a curved blade of 50cm or more, unless they're handmade using traditional forging methods, are antiques, or are used for specific religious, martial arts, or re-enactment purposes.
• In Australia, laws vary by state, but in general, it is legal to buy a sword. Some states may require a permit, especially if the sword is to be displayed in a public place.
• In Japan, swords that are considered nihonto (traditional Japanese swords) are national treasures, and buying one requires special permission from the government. These swords must also be registered with the local Board of Education.

Please note that these are general guidelines and the specific laws in your location may be different. Always check the local laws and regulations in your area. Also, keep in mind that even if it is legal to buy a sword, it might not be legal to carry it in public. Laws can change, and there may be additional local ordinances or rules that apply, so it's always best to check for the most current information in your specific area.