Here David speaks of Absalom and the men with him as "Absalom" himself because the men are following Absalom's authority. Alternate translation: "escape from Absalom and his men ... he and his men will quickly ... and they will bring" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
The "city" is a metonym referring to the people in the city. The "edge of the sword" is a synecdoche referring to the Israelites' swords and emphasize that they killed the people in battle. Alternate translation: "will attack the people of our city and kill them with their swords" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-synecdoche]])