Hi Mark,
The outstanding works on Spanish swords by Juan Perez can be found linked on Lee Jones article on the espada ancha located here on this site.
In looking at the bilobate guards on these military swords, I often have thought (in my typical free association way
of the Spanish shields of overlapping oval form termed 'adarga' and wondered if there was any association to the guards.
The Maltese (or St.Johns) cross is very much associated with Spanish religious and military symbolism, having to do with the military orders of the Knights of Alcantara and the Knights of Calatrava. Apparantly these orders adopted the red cross on white mantle from the Cistercians. References to Columbus in referring to the red crosses painted on the sails of his ships have varying perspective on the symbolic application. His association with Prince Henry of Portugal who was a Grand Master of the Knights of Christ, and whose symbolism of the red 'maltese' cross offers one possibility. However another reference is more general in stating that King Ferdinand of Castile-Aragon, for whom Columbus sailed, flew the 'Maltese christian cross on his sails'. Without going further with the complexities of the cross known commonly as 'Maltese' and its very widespread use symbolically, it does seem that it may have some amuletic or talismanic value in markings on weapons.
The application of the crosses on the sails may have been done in the same apotropaic sense that merchants marks with variations of crosses and 'anchors' were used to mark cargo and eventually weapons to protect them at sea.
Again, I cannot thank you enough for sharing these fantastic weapons here! This is definitely a thread that I know I'll be visiting often just to see them.
All very best regards,
Jim