The short answer is: steel. Even in the past, swords were forged primarily from steel, the "better iron". Due to its high elasticity and malleability, steel is easier to work with than iron.
The so-called "Damascus steel" is particularly prominent. Named after its homeland Damascus, this steel is a mixture of several types of iron and steel. It captivates above all by its handsome patterning.
Today, however, swords are mainly made of industrial steel using modern machinery. Info: Only decorative swords do not rust due to a higher chrome content. Swords made for fighting rust and require intensive care!