Several factors contribute to making a sword strong and capable of withstanding the rigors of combat or other demanding tasks. Here are some key elements that determine the strength of a sword:

1. Blade Material: The choice of blade material plays a significant role in determining a sword's strength. Different types of steel, such as carbon steel or tool steel, offer varying levels of strength, hardness, and toughness. The specific composition and heat treatment of the steel influence its overall strength and durability.
2. Heat Treatment: Proper heat treatment, including processes like quenching and tempering, is crucial for enhancing a sword's strength. Heat treatment optimizes the steel's hardness, resilience, and flexibility, enabling it to withstand impacts, retain its edge, and resist deformation or breakage.
3. Blade Geometry: The shape and geometry of the blade impact its strength. A well-designed blade with an appropriate thickness, taper, and fuller reduces weight without sacrificing strength. A proper distal taper, which means the blade gradually becomes thinner from the base to the tip, enhances the sword's balance, maneuverability, and resilience.
4. Tang and Hilt Construction: The tang refers to the portion of the blade that extends into the hilt. A full tang, where the tang extends the full length of the hilt, provides greater strength and stability. The construction of the hilt, including the materials and assembly methods, should also ensure a secure and rigid connection between the blade and hilt components.
5. Edge Geometry and Hardness: The edge geometry, specifically the bevel angle, affects both the cutting ability and the strength of a sword. A well-executed bevel angle ensures a sharp edge while maintaining sufficient material behind the edge to resist chipping or rolling. The hardness of the blade, achieved through appropriate heat treatment, contributes to its ability to retain a sharp edge.
6. Overall Design and Construction: The sword's design, including factors such as balance, weight distribution, and flexibility, affects its strength and performance. A well-balanced sword with appropriate distribution of weight and proper flexibility will handle stress and impact more effectively.

It's important to note that achieving a balance between strength, flexibility, and other desirable characteristics is crucial. Overemphasizing strength can lead to a sword that is overly rigid and prone to breakage, while neglecting strength can result in a blade that is too weak for practical use.

Crafting a strong sword requires the expertise of a skilled bladesmith who understands the interplay of these factors and has the knowledge and experience to select suitable materials, apply proper heat treatment, and execute the design and construction with precision.