As it so happens, there's another Arthurian relic that is very powerful and not as famous as the Grail and Excalibur. When I designed all four main Royal Relics, I knew one would be the most powerful and that I would save it for the last book.
Here's the title of the final book in the Le Fay series!
Spear -- Inspired by the mystical lance used in Arthurian tales that's been associated with the Spear of Destiny.
I'm looking forward to sharing the release date for winter plus cover reveal!