What message is the author sending the audience through the imagery of Montresor's coat of arms in "The Cast of Amontillado"? What does it symbolize?

The Montresor coat of
arms has a golden human foot on a sky blue background; the foot is stepping on a serpent rampant
which is turning and biting into the heel of the foot even while the snake is being crushed by
it. Montresor explains that his motto is "'Nemo me impune lacessit,'" which is Latin
for No one harms me with impunity; the word impunity
means without punishment. This motto makes sense with the arms image itself
because the image shows a snake being stepped on while it simultaneously turns back to bite the
foot that is trampling it. The snake does not allow the foot to injure the snake with impunity;
the snake punishes the foot (and the person attached to it) for harming it by biting the
foot.

This seems to indicate that the Montresors are a proud family, and one
cannot injure a Montresor without expecting some kind of terrible retribution, some inevitable
payback or revenge. If we weren't already sure, this is one way that Poe lets us know that
Montresor means to do irreparable harm to his enemy Fortunato. The arms symbolizes his proud
need to repay Fortunato for the supposed injuries and insults Fortunato has offered him. This
could also be why the Montresor family was, in the past tense, "a great and numerous
family." Perhaps they have made too many enemies!