In Edgar Allan Poe's short story, Fortunato, the man whom Montresor plans to kill, asks Montresor about the coat of arms of the latter's family:
"I forget your arms."
"A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel."
"And the motto?"
"Nemo me impune lacessit."
The motto means "no one insults me with impunity."
These arms are obviously relevant to the story as a whole: Montresor feels that he has indeed been insulted by Fortunato. He plans to kill Fortunato (that is, he plans to crush the serpent). The detail suggesting that Fortunato's fangs have been buried in Montresor's heal can be read in at least two ways: Montresor feels that he has been injured by Fortunato; Montresor, even though successful in killing Fortunato, will be troubled by the killing for years afterward.