While it is technically possible to sharpen a sword using sandpaper, it is not the most efficient or recommended method. Sandpaper is not designed for sharpening blades and may not provide the desired results in terms of sharpness and edge quality. Here's why:

1. Grit Size: Sandpaper is available in various grit sizes, typically ranging from coarse to fine. Coarser grits can remove material quickly but may leave scratches and a rough finish. Finer grits can produce a smoother surface but may take a longer time to remove material and may not achieve a truly sharp edge.
2. Consistency: Achieving a consistent and precise bevel angle on a sword edge is challenging with sandpaper alone. Maintaining a consistent angle throughout the entire length of the blade is crucial for an even and uniform edge.
3. Blade Material: Different swords are made from various types of steel, each with its own hardness and characteristics. Sandpaper may not be able to effectively remove material from harder steel types, especially if they have been heat-treated to achieve higher hardness levels.

If you want to sharpen a sword properly, it is recommended to use dedicated sharpening tools specifically designed for blades. These tools include sharpening stones, honing rods, or sharpening systems that offer consistent angles and precise control over the sharpening process. These tools are better suited for maintaining the proper bevel angle, removing material evenly, and achieving the desired level of sharpness.

For optimal results, it is advisable to consult with an experienced bladesmith, knife sharpener, or professional sharpener who can guide you through the proper techniques and tools required to sharpen a sword effectively and safely.