The sharpest sword ever made is a matter of debate and subjective opinion. Throughout history, many different swords were renowned for their exceptional sharpness and cutting ability. Here are a few notable examples:

1. Damascus Steel Swords: Swords made with traditional Damascus steel are often praised for their exceptional sharpness. The unique layered structure and high-carbon content of Damascus steel blades allowed for a keen edge and excellent cutting performance.
2. Japanese Katana: The Japanese katana is renowned for its sharpness and precision. The careful crafting and specific heat treatment processes used by Japanese swordsmiths, combined with the high-quality Tamahagane steel, contributed to the katana's reputation for exceptional cutting ability.
3. Urumi: The Urumi is a flexible sword from India, consisting of multiple thin and flexible blades attached to a single hilt. Due to its flexible nature, the urumi can deliver cuts with a high level of precision and reach, making it unique in terms of sharpness and versatility.
4. Gurkha Kukri: The Gurkha kukri, a traditional Nepalese knife with a distinctive curved blade, is known for its exceptional sharpness. The inwardly curved shape concentrates the force of the cut, enhancing its cutting ability.

It's important to note that the sharpness of a sword depends not only on the quality of the steel but also on the craftsmanship, heat treatment, and the sharpness achieved through proper sharpening techniques.

Ultimately, the "sharpest" sword depends on various factors, including the specific design, materials, and the skill of the smith. Moreover, the perception of sharpness can also be influenced by personal preferences and cultural context.