Yes, it is possible to sharpen a dull sword. Sharpening a dull sword can restore its cutting ability and improve its overall performance. However, sharpening a sword properly requires skill, knowledge, and the appropriate tools. Here are some general steps to sharpen a dull sword:

1. Assess the Sword: Examine the sword to determine its condition and the extent of the dullness. Identify any nicks, chips, or other imperfections that may need to be addressed during the sharpening process.
2. Choose the Right Tools: Select the appropriate sharpening tools for the type of sword and the level of sharpening required. This may include various types of sharpening stones, honing rods, or other specialized equipment.
3. Secure the Sword: Ensure the sword is securely mounted or clamped in a stable position before beginning the sharpening process. This provides stability and safety during the sharpening procedure.
4. Sharpen the Blade: Depending on the tools chosen, follow the appropriate sharpening technique. This typically involves running the sharpening stone along the blade's edge at the correct angle, using smooth and controlled motions. Repeat the process on both sides of the blade until the desired sharpness is achieved.
5. Address Imperfections: If there are nicks or chips along the blade, those can be addressed using specific techniques such as filing or grinding. However, extreme care should be taken to preserve the blade's shape and integrity.
6. Test and Refine: After sharpening, carefully test the blade's sharpness on appropriate materials. Make adjustments or further refine the edge if needed, ensuring a balanced and consistent edge.

It's important to note that sharpening a sword requires expertise, especially when dealing with historical, valuable, or antique swords. If you are uncertain or lack experience, it is recommended to seek the assistance of a professional swordsmith or experienced sword sharpener. They can ensure that the sharpening process is conducted safely and effectively, preserving the integrity of the sword while achieving the desired level of sharpness.