The Orlando Innamorato in English translation, Book I, Canto II, Part 1, Stanzas 1-20, Notes
1. Magic armor. Similar armor appears in a few romances, but not in very many as it tends to kill the possibility of suspense. Boiardo solves this problem cleverly, as we shall see in Canto III.
Magic skin. This characteristic of Ferraguto’s is traditional. Much later, Orlando will kill him after discovering his secret, shortly before the battle of Roncesvalles. Orlando has a similar enchantment on his skin, which he received as a gift from Saint James of Compostela. (This detail, while also traditional, is later than The Song of Roland) His weak point is the soles of his feet. This naturally creates a problem for authors, as he has to die at Roncesvalles. In Pulci, he dies of exhaustion. In Spanish romances, Bernardo del Carpio strangles him, as Hercules did the Nemean Lion. The ultimate source of this magic skin is, of course, Achilles and his vulnerable heel. See also Siegfried, who obtains invincibility by bathing in dragon’s blood, but doesn’t notice a leaf keeping part of his back dry.