The phrase 'gives a black eye' means to tarnish one's reputation or make them look bad. Some antonyms of this phrase could be 'boosts prestige,' 'elevates reputation,' 'enhances image,' or 'improves standing.' These words indicate that the action taken by the person is beneficial and adds value to them, which is the opposite of giving someone a black eye. So when we want to describe actions that make someone look good, we should use such antonyms. For instance, a great business decision could improve someone's standing, and a good charitable act could enhance their image in the society.