Weirbooks' are books that all Weir members receive at birth, along with their Weirstone. The Weirbook is created when the Weir is born by a sorcerer, and is made specifically for them. Weirbooks are indestructible and therefore are artifacts sometimes possessed by others ling after their subject's deaths.
Inside the weirbook outlines the Weir's entire family tree, as well as their strengths and weaknesses. This makes it dangerous as if the Weirbook falls into enemy hands, then the enemy would know the Weir's strengths, weaknesses, and loved ones and would be able to exploit them. In wizards, ere is also a section devoted to spells and charms which are either passed through the family or that the wizard would have an affinity for.
Upon the birth of an heir, a weirbook is made. Traditionally, the parents of the child with go to a member of the sorcerer guild and have them make it, using a family weirbook as a template. However, in mixed-blooded families, it becomes more complex. The closest weir relative, an aunt for example, would use their own as a template. The book is then gifted to that person to give to its subject at their discretion. It is unknown how weirbooks are created for those with no known weir relatives, though it is certain that they do indeed have them.