The concept of the "most durable sword" can be subjective and depends on the specific criteria and context in which durability is being evaluated. Different types of swords are designed for various purposes, and their durability can vary based on factors such as the materials used, construction techniques, and intended use.

That being said, some swords are known for their durability and toughness. Here are a few examples:

1. European Longsword: The European longsword, popular during the medieval period, was often made with a strong cross-section and robust construction. It was designed for both cutting and thrusting, and its durability was crucial for withstanding the rigors of battle.
2. Japanese Katana: Traditional Japanese katanas were crafted using a combination of hard and flexible steel layers, resulting in a blade that is both sharp and durable. The folding and differential hardening techniques used in their construction provided strength and resilience.
3. Viking Sword: Viking swords, such as the iconic double-edged pattern-welded swords, were renowned for their durability. These swords featured a combination of hard and soft steel layers that made them both strong and flexible, allowing them to withstand intense combat.
4. Chinese Jian: The Chinese jian, a double-edged straight sword, was often crafted using high-quality steel and advanced forging techniques. These swords were known for their durability and balance, making them effective weapons in Chinese martial arts.

It's important to note that the durability of a sword is not solely determined by its design or type but also by the quality of craftsmanship and materials used in its construction. Skilled swordsmiths, modern metallurgy, and high-quality production techniques play a significant role in creating durable swords.