Here "you" refers to Mount Seir, but the message is for the people of Edom. The abstract noun "desolation" can be stated as an adjective. Alternate translation: "Because of what your people did I will make you desolate" (See: [[rc://en/ta/man/translate/figs-personification]] and [[rc://en/ta/man/translate/figs-abstractnouns]])
Here "earth" represents the people of the earth. The word "entire" is a generalization that refers only to people near Mount Seir. Alternate translation: "people who know that I have destroyed you rejoice" (See: [[rc://en/ta/man/translate/figs-metonymy]])