I suspect "Jagger" relates to Mick Jagger, singer of the Rolling Stones. "Swagger" has become a very cool word recently though its "cool" meaning is related to its real meaning. "Swagger Jagger" is not a phrase with a clear meaning on its own. Perhaps some journalist has noted that the words rhyme and wanted to attract attention to his or her article. Can you give more context and we may be able to help better?