Moses addresses the peoples of all the nations as if they were there listening. (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-apostrophe]])
Here "blood of his servants" represents the lives of his innocent servants who were killed. Alternate translation: "for he will take revenge on his enemies, who killed his servants" (See: [[rc://en/ta/man/translate/figs-metonymy]])