Cadescing Ether - the most infamous term in the Modern Jujutsu Society; even mentioning it raises eyebrows. Cadescing Ethers are ancient weapons infused with primordial cursed energy, which gives them a "will of their own".
Cadescing Ethers either choose their righteous wielder; the wielder usurps their power, making the weapon obey them, and in turn gaining a suitable suffix; or the cursed tool yields itself to the wielder, which is similar in benefits as usurpation, but the Cadescing Ether will now be at peace.
They are the apex of cursed tools, and their whereabouts are a mystery even to Master Tengen.
There is only one known Cadescing Ether "The Inverted Spear of Heaven", which was previously wielded by Toji Fushiguro. The cursed tool deemed him righteous to use its power, hence not attaining the signature suffix.
Cadescing Ethers are considered heresy, an attack to jujutsu and sorcerers as a whole, and have been strictly forbidden.
Additionally, if the Cadescing Ether chooses its wielder, then its base properties are not altered nor expanded. If the wielder subdues the power within it, or the Cadescing Ether yields itself to the user, then they can influence its properties and appearance.
Anyone who wields one of these mighty cursed tools forms a bond with them depending on each other's personality.
Cadescing Ethers are to be considered a top priority threat to the Jujutsu Society.