Dénouement

Denouement is the name of the spear acquired by The Celestial/Murderers in Session 15: The death of a demigod. It has the appearance of a mundane wooden spear, with small inlaid carvings of spears all along the shaft. The one outward indication that this is anything other than a mundane spear is that the tip is constantly dripping blood, defying all attempts to dry or clean it off regardless of how long it has been since the spear was used.
The party learned in Session 22: Trial, Part 1 that the spear was war spoils during The Shattering that the spear cannot be manipulated, let alone destroyed, by immortal beings. It was also thoroughly established that the gods are terrified of this weapon. Zerrof has postulated that it is somehow related to the end of the world.

/*The spear was originally owned by Iapetus, god of mortality. Its power is to impose mortality on any being struck by the spear. This can be used for good or ill: deceased humanoids are restored to life, but immortal beings, gods included, suddenly find themselves subject to the aging process. In the case of gods this often comes with other side effects, namely a significant reduction in power. This has already happened to some of the currently living gods, and is also why the Duke of Air the party encountered during Session 15: The death of a demigod was weak enough for the party to slay.
Exactly which gods have been afflicted with mortality in this way remains a closely guarded secret.*/