It helps to think of older terms and how they relate to more-common modern terms. "Benediction" is a synonym for one sense of "blessing" — the sense that means

It helps to think of older terms and how they relate to more-common modern terms. "Benediction" is a synonym for one sense of "blessing" — the sense that means "to speak good upon" (bene- and -dict). Conversely, a synonym for one sense of "curse" is "malediction", which is the opposite of "benediction": "to speak bad/evil upon" (mal- and -dict).