No, that's not a 17th century poisoner's book

This book, which was hollowed out and contained several tiny drawers and a glass bottle, was presented as a "Medieval" poison cabinet, "bound around the year 1600" and an "Assassin’s arsenal" in places around the web - the writers of these articles failed to notice that the auction house that was selling it listed it as a " Historism, 17th-century style.", which in Germany means something that is a reproduction meant to look like something made in a past age. The date that the artifact was made was not estimated, but the art movement that produced historisms flourished in the late 19th and early 20th century. Parts of the artwork could be older, like the engraving that was pasted on the inside cover, or the cover that the auction listing says is from 1600, but the final product was finished much later.

(Image via Imgur)

Hermann Historica auction listing for item

And here is a listing for a similar book that looks like it was made by the same artist, that dates it to the 19th Century:

Michael Zeller Auction House

and another similar one sold by Hermann Historica

The artist is making an untranslatable joke here - these are called Giftschränkchen - 'little poison cabinet' - literally a poison cabinet is a place where medicines that could be dangerous were kept, but a Giftschrank is also a place in a library where books that were restricted circulation were kept - after the war these could include Nazi literature like Mein Kampf. So it's a book that's a poison cabinet that should be in a poison cabinet!
There is an anachronism in the piece that shows it wasn't made in the 17th century - I'll leave it to the reader to find it!