Join Date: Mar 2016
May I ask what sources are you referring to? To the best of my knowledge, the only study of the (Falces) Tizona's metallurgy is that performed by Antonio Jose Criado and his team, which concluded "the blade was forged from low-carbon steel, and subsequently a surface layer... was produced by carburizing." Alan Williams has written that this metallic structure "differs little from many other examples of medieval swords, axes, and knives... such a blade might have been produced almost anywhere in Europe over a thousand years from Roman to Early Modern times."
According to family tradition the sword was a gift from King Ferdinand, which is plausible, but there is apparently no (surviving) evidence to corroborate this story. As mentioned in my article (and by Gonzalo above), the earliest source that confirms that the sword was owned by the marquis of Falces is Prudencio de Sandoval, in a chronicle published in 1615. Sandoval saw the sword in person, but instead reports that he was told it had been directly inherited from El Cid by the kings of Navarre, then given to an unnamed family ancestor. This version is not believable in itself, but it does not exactly bolster the case for the traditional story...
Criado et al, "Metallographic study of the steel blade of the sword Tizona," Praktische Metallographie (2000).
Williams, "Science and fakery: the limitations of science in the analysis of arms and armour," Journal of the Arms and Armour Society (2006).