Nahum speaks of fire burning and destroying as if it were eating. Alternate translation: "Fire will destroy you there" or "Your enemies will burn you with fire there" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here the word "sword" is a metonym for the enemies who will attack with swords. Alternate translation: "your enemies will kill you with their swords" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The word "It" refers to the "sword," which is personified as eating those whom it kills. The soldiers using their swords to kill everyone in Nineveh is compared with the way that a swarm of locusts eats every plant in its path. Alternate translation: "Your enemies' swords will kill all of you, just as easily as a swarm of locusts devours everything in its path" (See: [[rc://en/ta/man/translate/figs-personification]] and [[rc://en/ta/man/translate/figs-simile]])