Having the power over something is spoken of as having the keys to it. The implied information is that he can give life to those who have died and let them out of Hades. AT: "I have the power over death and over Hades" or "I have the power to give life to people who have died and to let them out of Hades" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-explicit]])