"Journal 4"

It's old, thick, and bounded by leather.

A journal that Helen (Cate's mother) owned. It was written by an intelligent witch from long ago and discusses theories and machinations of magic unheard of for several centuries. Its also a diary of sorts, as the witch who wrote it talks about their personal life.

Leather, paper, and ink.

10 lbs maybe

Long af time ago

It's just a book; no magic

There are several things that reveal little characteristics about the author of the journal
They were an alchemist witch
They were a part of the project that created the Guardians
They were aware of a 'secret magic' that only one Necrotzen every generation could wield
They were friends with a Kleiname
Their name started with a 'P'
They are most likely dead