In his most optimistic (or deluded) moments, Willy borrows from Classical mythology in order to describe his sons.
"Adonises”
Willy is thrilled by the idea of the Loman Brothers partnership and assures his sons they are “both built like Adonises”, the ancient Greek symbol of male beauty.
“Hercules”
Elsewhere, he compares Biff to “Hercules”, the Roman God famed for his strength.
Willy also uses cosmic imagery associated with the ancient Gods, calling Biff a “star”.
Irony
These motifs help to elevate (raise up) these characters in order to give them a more heroic status (Biff himself uses similar language in calling his father a “prince”).
However, they may have been used ironically by Miller as we, the audience, see Willy’s boys in a much more realistic light.