This expression refers to the person who would bring salvation—the infant Jesus—whom Simeon was holding. AT: "the savior whom you sent" or "the one whom you sent to save" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This metaphor means that the child will help people to see and understand the same way light helps people see accurately. AT: "this child will enable people to understand as light allows people to see accurately" (See: [[rc://en/ta/man/translate/figs-metaphor]])