I dunno, that's like saying because Kress's abacus is made of wood, it's a weapon because folks have been beating each other with sticks since forever.
@TheWendil Those tomes never take the shape of a weapon. It has to be something that "formulas" can be inscribed to like the ones ERode mentioned. While Kress's tome is the furthest from a book, it still has set formulas to produce spells and a way to manipulate the mana e.g. adding the spell components in a correct manner.