I think this subject may interest some people,
One of my concern on the 1st Pillars Of Eternity was that we'd get to know & see, every possible Enchantments we could do, like, from the very begining of the Game.
And never had the opportunity to find that great treasure containing that awesome new Recipe for Weapons, Armor, Shields or Hats.
Pretty sure it was a lack of time and ressources problem for you to make it happen.
But now, killing Concelhaut, or Any Archmage should have this feature in Deadfire.
Sneaking in his/her own private Library, looking for Unique Spells & Enchantments that only a powerfull Archmage know about.
If I'm a Rogue, or have a Rogue, and sees that, an Archmage keeps his personal Grimoire in his desk.
I'd like to have the possibility to sneak in at night, and steal it !
Obviously, Yselmir should manisfest & tell the Hero : "Hey, why not steal this Grimoire from him ?".
Of course, Aloth, like the p*ssy he is, (I like Aloth...^^) would instantly disagree : "You can't do that ! it's one the most powerfull Mage's Grimoire in Eora, he must have protected it with all kinds of dangerous spells ! Even put a Curse that prevent others to use it !" etc, etc.
Ok, all of this to say, I'd like Unique (hidden) Recipes in terms of Enchantments primarily, and maybe Weapons & Stuff in Deadfire.
I hope they will be able to push that feature further this time around.