An ancient history book shows records of contests of strength in which athletes would spin balls of steel at great speeds, and launch them into the air to see whose ball traveled the farthest. Could this ball be from such a contest?
The Sailors' Guild will have this discovery's information (not the location) for sale, described as "Pride of the Victor?".
This discovery is in constant motion, and is very fast (almost at the top speed of the Delphinus.) It is extremely nimble for a discovery, and covers a great distance. It will travel in an enormous oval-shaped path back and forth across upper sky. The Flying Flail's commute takes it around the summit of Mount Kazai, across the entire breadth of the Valuan continent (heading dead west) across north ocean, where it will turn back around halfway across Looper territory (now heading dead east) and complete the circuit, where it will turn back again.
The most recommended means of discovering this discovery is to enter the Valuan lower city (while it is still in one piece), exit, and climb immediately to max altitude, looking north. The flail should go whizzing by, appearing to be some sort of black yo-yo, giving the player a chance to catch it. The flying flail object is generated in the vicinity of the skies above the "ancient palace" discovery. As entering and exiting a city resets the "tracks" of all moving discoveries, this should almost always work. Saving and restarting will also cause this discovery to reset if done later in the game.
Alteternatively, one can save and restart the game while facing W, positioned in Upper Sky, above the Ancient Palace discovery to easily locate this discovery.