The notion of the "greatest" sword ever made is subjective and can vary depending on individual perspectives, historical context, and cultural significance. Different swords have excelled in various aspects such as craftsmanship, design, historical impact, and cultural influence. Here are a few swords that are often considered among the greatest:

1. Katana: The katana, a traditional Japanese sword, is widely regarded as a masterpiece of craftsmanship and design. It embodies the refined techniques of Japanese swordsmithing and is renowned for its sharpness, balance, and cutting ability. The katana holds a special place in Japanese culture and is associated with the samurai warrior class.
2. Ulfberht Sword: The Ulfberht sword is a medieval Viking sword that is highly regarded for its quality and technological advancements. It was made from high-quality crucible steel, a material far superior to what was typically available during that era. Ulfberht swords were highly sought after and became a symbol of status and wealth.
3. Excalibur: Excalibur is the legendary sword associated with King Arthur in Arthurian legends. It is said to possess extraordinary qualities, including being unbreakable and bestowing its wielder with invincibility. Excalibur represents the pinnacle of mythical swords and has captivated imaginations for centuries.
4. European Longsword: The European longsword, prevalent during the Middle Ages, is considered a versatile and effective weapon. Its design and use evolved over time, with various regional variations and techniques. European longswords were admired for their balance, reach, and adaptability in both one-on-one combat and on the battlefield.
5. Chinese Jian: The jian, a traditional Chinese double-edged straight sword, is highly regarded for its elegance, precision, and craftsmanship. It has a long history dating back thousands of years and symbolizes the martial traditions of China. The jian is renowned for its balance, flexibility, and harmonious blending of form and function.

It's important to note that the perception of the "greatest" sword can vary based on personal preferences, cultural influences, and historical significance. Each of these swords has made an impact in its respective cultural context and represents a pinnacle of craftsmanship, design, or mythology.