Page "Sword" Paragraph 76

Broad blades often have grooves known as fullers which lighten the blade while conversely increasing its strength and stiffness.

Narrower more pointed blades achieve a similar effect by the use of a flattened diamond cross-section with a raised central ridge.

In many swords both methods were combined to give a dual purpose weapon.

Blades developed purely for thrusting are usually of triangular cross-section with no real cutting edge.