The "heart" was associated with emotions. The Edomites' pride caused them to be deceived about their security. AT: "Your pride has deceived you" or "Your pride causes you think you are safe" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This question expresses that the Edomites were proud and felt safe. AT: "No one can bring me down to the ground." or "I am safe from all attackers." (See: [[rc://en/ta/man/translate/figs-rquestion]])