Odysseus calls the "fair wind" sent by Circe a "welcome comrade." So, in this metaphor, he compares the wind that pushes their boat forward, speeding them on to the next leg of their journey, to a good friend because, hopefully, it will bring them one step closer to getting home! Also, Odysseus describes the "Cimmerian people's land and city [as] wrapt in a fog," and he says that "deadly night is spread abroad." In both cases, the comparison is to a mantle of sorts. The fog wraps around the city like a blanket or cloak, and the night is spread over the land like a blanket. Remember that Odysseus is telling a story, and these sorts of poetic devices enliven his tale and beautify it. They give the story a more imaginative and fantastic quality.
In addition, when Odysseus sees Alcmene, the deceased mother of Hercules, he refers to Hercules as "lion-hearted." This, too, is a metaphor, comparing Hercules' immense power and courage to a lion.