Final answer:
Montresor's coat of arms features a golden foot crushing a serpent, symbolizing his family's power and response to betrayal, with the foot representing the family and the serpent representing Fortunato's treacherous act against them.
Step-by-step explanation:
Montresor's family's coat of arms is described in Edgar Allan Poe's short story The Cask of Amontillado. The coat of arms portrayed a huge golden human foot d'or, in a field azure (blue); the foot crushes a serpent rampant whose fangs are embedded in the heel. The symbolism of the coat of arms is crucial to understanding the story's themes of revenge and betrayal.
The foot represents Montresor's family, standing firmly and powerfully, while the serpent represents the treacherous act committed against the family, which Montresor believes is embodied by Fortunato, the man he seeks to punish. The imagery of the serpent biting the heel relates to the act of betrayal that has wounded the family's pride.