The phrase "passed oneself as" implies that someone is pretending to be someone or something that they are not. Antonyms for this phrase might include words like "revealed one's true identity," "acknowledged," "admitted," "disclosed," "confessed," or "owned up to." These words suggest a willingness to be honest and open about one's identity and actions, rather than attempting to deceive others. Other possible antonyms might include words related to authenticity, such as "honest," "genuine," "real," or "authentic." These words emphasize the importance of being true to oneself and others, rather than pretending to be someone or something that one is not.