World Weapon Encyclopedia is a book found in Radiata Castle's library.
When Jack Russell chooses to look inside it he reads:
The most famous weapons in the world are the Avcoor, a legendary weapon from the period of the fairy wars and also the holy sword, Falvern. These are the most famous weapons in existence. There are others that are heard of only in legendary takes. There are named after the gods, such as Efreet, Leviathan, Jinn and Behemoth. However, these weapons are probably mythical and never actually existed.