Grave talhor degli altri arnesi e carco
Ruperto hebbe, e 'l fratello, il petto e 'l dorso;
Ma di questa ei sol volge in grave incarco,
Che diè vittoria a' suoi, non pur soccorso;
Et armato n'andria leggero e scarco
Come l'huom nudo o pur destiero al corso,
E sembraria pardo o leone al salto,
Dando a feri nemici il fero assalto.
Sometimes Rupert or his own brother had their
Bodies burdened with Richard's parts of armor,
But he alone handles his heavy sword, which
Often gave victory, not only help, to his army.
Armed with nothing more than it, he could go
Light as a naked man or a running steed,
And would look like a jumping leopard or lion
Fiercely attacking his fierce enemies.
This stanza/octave also has been added in Gerusalemme Conquistata. Since a key-episode in the final section of the poem will be Rupert's death, caused by the fact that he had Richard's armor on (as it had happened to Patroclus in the Iliad), here Tasso allusively prepares that scenario by mentioning other occasions in which Rupert was given Richard's armor -- mentioning it, moreover, in this "fatal hour" in which Richard must leave the Christian camp, that will be the beginning of all troubles.
The hint at Richard's brother is simply a filler: what really matters is Rupert receiving Richard's armor. This implicitly refers to their love (again, like Patroclus and Achilles in the Iliad), although, in the general structure of GC, this "gay" novelty will basically pop up all of a sudden, almost out of the blue, after Richard has undergone the same adventures as the heterosexual Rinaldo had in Gerusalemme Liberata, his love story with the beautiful witch Armida included.
The theme of the special, lethal, unique sword of the hero -- maybe savagely using it with no armor on, like Conan -- is a "must have" in fantasy literature. In this case, however, it is only about an "appetizer"; Richard will benefit from a much more powerful armory in the last Cantos of the poem.