Recently, there was a post by Kiritsugu suggesting that venom bomb be made universal, due to how integral it is to mage DPS.
This got me thinking - how to make it universal but also not kinda clunky?
Then an answer arose, tomes. A tome would be drops from high level activities (dungeons, bosses, what have you) and would occupy the mage offhand slot. This tome will hold magical secrets, or, perks, allowing you to choose between those you have unlocked.
To this end, webbed staff will no longer have venom bomb as an innate perk - instead, the secret of ven bomb will be a reward from SQR. ( New perk for Webbed could buff puddle damage).
With the new death penalty coming up, a potential punishment could be a chance of losing a secret from your book. Such a chance would be reduced by having a higher level tome.
On the topic of higher level tomes, high-level tomes may allow you to have two perks at a time, or some other benefit.
Edit: people like this idea way more than I anticipated