Yes, katanas do need to be sharpened regularly to maintain their cutting ability. A sharp blade is essential for a katana's functionality and effectiveness. Over time, the cutting edge of a katana can dull due to use, contact with surfaces, or exposure to the elements.

Sharpening a katana requires skill and expertise, and it is typically done by professionals who specialize in sword maintenance or restoration. The process involves removing any nicks or imperfections on the blade, refining the edge geometry, and honing it to a razor-sharp state.

It's important to note that sharpening a katana should be approached with care to preserve its historical or cultural value. In the case of antique or valuable katanas, it is often recommended to seek the services of a reputable and experienced swordsmith or restorer who understands the specific requirements of maintaining such swords.

Regular maintenance and care of a katana, including sharpening when necessary, are important to ensure the blade remains in optimal condition. This helps maintain the cutting ability and longevity of the sword while preserving its historical or cultural significance.