What is the significance of Montresor's family coat of arms and motto?

"The story begins with Montresor explaining that the man Fortunato has given him many insults and that Montresor must get his revenge for them. The family motto is Nemo Me Impune Lacessit, which essentially means Montresor's family will permit no man to impugn its honor. The crest of the family arms is that of a foot crushing a snake that has its fangs in the foot, meaning that someone my try to harm the family but the family will kill whoever tries. This is exactly what Montressor does to Fortunato."