Yahweh repays them by punishing them. This can be stated clearly. Alternate translation: "Yahweh has punished" (See: [[rc://en/ta/man/translate/figs-explicit]])
Here "blood" refer to people who were killed from Saul's family. The king was responsible for them dying. Alternate translation: "for killing many of Saul's family" (See: [[rc://en/ta/man/translate/figs-metonymy]])
David reigned as king over the same people whom Saul had previously reigned. Alternate translation: "in whose place you have reigned as king" (See: [[rc://en/ta/man/translate/figs-explicit]])