The Sceptre of the Ancients was an incredibly powerful tool used by The Ancients to kill the Faceless Ones. It was a golden rod, about the length of a thigh bone and had a Black Crystal embedded into it's hilt. It sang to its owner when someone approached it but stayed quiet when an Ancient (or a person with Ancient blood) approached. The Sceptre was a focusing tool for the black crystal and shoots out black lightning that turned anything it came into contact with to dust. Once the previous owner had died, all one needed to do take ownership was to touch it.
Serpine killed Gordon Edgley to gain the key to access the Caves. The Sceptre was contained in the the Caves. Serpine stole the Sceptre and used it to kill Eachan Meritorious and Morwenna Crow, and later kills Sagacious Tome even though he was on his side. The Sceptre was used to kill the Elders so he could get the Book of Names so he could rule the world. However, Skulduggery tricked Serpine into using the Sceptre to destroyed the Book, and not long after Skulduggery Pleasant takes it from Serpine and uses it to kill him. The Black Crystal is destroyed after Serpine is killed. China Sorrows was then given the Spectre to add to her obsessive collection of magic.
Valkyrie and Skulduggery obtain a new Black Crystal for the Sceptre when the Faceless Ones escape through the portal between realities. Valkyrie Cain became the new wielder of it and accidentally destroyed two bookcases that China Sorrows owned by mistake. The Sceptre was used to successfully kill a Faceless One, but another manages to destroys the Spectre and the Black Crystal within it and in doing so destroyed itself. The third and final Faceless One was forced back through the portal in its vessel, with considerable effort required. It dragged Skulduggery with it, into the opposite reality.
Another alternate version of the Sceptre was still in perfect condition in the Parallel Dimension but was in the throne room of Mevolent's Palace. It was retrieved by Skulduggery and Valkyrie, with the aid of the Serpine in that reality, and taken by China just before they shunt back. It was later retrieved by Darquesse the next and last time she shunts, but was dropped and stolen by Valkyrie Cain's reflection, unbeknownst to anyone but her.
The Reflection still had the sceptre when the reflection went rouge, and attempted to kill Valkyrie with it. She failed, and didn't use until the Battle of Roarhaven, when she became an ally of Skulduggery Pleasant. She accidentally allowed Alice Edgley to touch the crystal, but it didn't kill her as she was descended from the Ancients. The reflection didn't check to see if the rule applied to reflections.
Stephanie (Valkyrie Cain's reflection) was still in possession of Sceptre following the events of Last Stand of Dead Men and was using to Hunt down the Renegades (Super-charged Sorcerers) and she also used it in her confrontations with Darquesse and other sorcerers. After Stephanie was murdered by Darquesse, ownership of the Sceptre passed on to Alice, as Stephanie hid it under her mattress, and Alice accidentally took ownership.
In order to fight Darquesse, Valkyrie had to somehow take control of the Sceptre. Consequently, she forces herself to kill Alice, so she could take ownership of it, for which she never forgave herself. By the laws of the Sceptre, it bonded to Valkyrie - only to be thrown straight off the planet by Darquesse. That was the last of the Spectre of the Ancients in the Skulduggery Pleasant series.