FASA Games, Inc.

The Barrier Rating Table is in the Gamemaster's Guide, forthcoming. Here's the table, copied from the galley proof:

Barrier Rating Table

I see nothing about grimoires.

I would set the stats for a grimoire, usually a fairly chunky book, equal to Wood 2". Have you ever tried to tear a book in half? There's a reason why ripping a phone book is a demonstration of incredible strength. However, if the character chooses to have their grimoire be a strand of engraved beads, I'd alter the stats accordingly. I've made a note that this is Errata, and that we should add a table with typical Grimoire PA and BR stats to the next printing.