The idiom "to fall by the sword" means to die in battle. This can be stated in active form. Alternate translation: "I will enable their enemies to kill them with swords" (See: [[rc://en/ta/man/translate/figs-idiom]] and [[rc://en/ta/man/translate/figs-activepassive]])
The verb may be supplied from the previous phrase. The idiom "fall ... by the hand of" means to be killed by someone, with the word "hand" representing the whole person. Alternate translation: "I will enable those who want to kill them to kill them" (See: [[rc://en/ta/man/translate/figs-ellipsis]] and [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-idiom]])