To maintain your katana blade, clean it after each use by wiping off moisture, fingerprints, and debris with a soft cloth. Apply a light coat of oil, such as mineral oil, to prevent rust and corrosion. Regularly polish the blade with a proper cleaning kit to remove oxidation and maintain its shine. Avoid touching the blade directly with bare hands, as oils from skin can cause rusting. Finally, sharpen the blade occasionally using appropriate sharpening tools to retain its edge.