Hi, it’s Junko from Japan. “Sacred treasure swing and ring” is a magic spell Fushiguro Megumi chanted when summoning YATUKA NO TSURUGI IKAI SHINSHO MAKORA (eight-handled sword divergent Silla divine general Mahoraga) with the Ten Shadows Technique. The original Japanese phrase says FURUBE YURAYURA. Here are the Kanji symbols for it.
FURUBE = means “shake something” in the ancient Japanese
YURA YURA = onomatopoeia to describe something is swinging
This phrase comes from an ancient Japanese history book titled SENDAI KUJI HONGI (previous ages old things chronicle) published around the 800s. “sacred treasure swing” is a part of the sacred spell written in the book. It’s said if you cast this spell and swing the ten treasures, they trigger tremendous power which is powerful enough to revive even the dead.
Here you can see the drawings of the sacred ten treasure recorded in an ancient Japanese print. The eight-handled sword is placed on the second row from the top. A flower-like figure with eight corners is the one.
Jujutsu Kaisen borrows many settings from Buddhism and the Japanese Shinto religion. Fushiuro Megumi’s Ten Shadows Technique is also based on the ten treasures legend in the Japanese Shinto myth. Therefore some Japanese fans guessed that Sukuna was trying to revive himself by using the power of the sacred ten treasures. But he destroyed Megumi’s familiar Mahoraga, which means one of the ten treasures had been lost forever. So Sukuna’s true intention stays unknown.