Usually, the tome pages are only lit while you're in a tome - my speculation is that the tome pages are now shared between books, and recover slowly over time or after doing certain actions (the extra page on triggering F1 passive springs to mind).
Probably doesn't change much for builds that use only one tome, but is a significant hit to the flexibility of quickly flipping through the tomes. Allowing players to make tradeoffs in the moment as to whether they need more damage from F1, a cleanse from F2, or stab from F3 seems like a pretty gameplay to me.
I will be interested to see if the tomes are retaining their original cooldowns, or whether they'll act more like kits or weaponswap and have lower cooldowns, relying on the shared pages as the limiting factor instead. I suspect that the missing weapon is a false lead, as that combined with this nerf to books feels like too much of a nerf to me, but we'll have to wait and see.
I also don't think the signets mean much - since they got reworked/buffed recently I doubt there's any significant change to them.
