In Chapter 19: The Foot Of Apollo, you will have to use a lever to activate a platform. The platform will then start to move, and Harpies will attack you. Press Circle to punch one of them with the club, and they will fall down into the ocean and die, and you will get the "Swinger" trophy. Note: The club is found at the very end of Chapter 18, after solving the chain puzzle. If you are doing this through chapter select, load Chapter 19 first to see if you already have the club in your inventory. If not, you will need to replay Chapter 18 to get it.