What metaphors are used in What We Talk About When We Talk About Love by Raymond Carver?

In the story, What We Talk About When We Talk About Love, Nick, the narrator, points out to Mel that the armor worn by knights had its drawbacks. Nick's comment extends the metaphor of the armor as emotional armor in explaining that one's emotional defenses, or armor, can end up suffocating the knight in the name of protecting him from harm: "But sometimes they suffocated in all that armor, Mel. They'd even have heart attacks if it got too hot and they were too tired and worn out."