I found an easy way to custom make Books that teach the player missing spells.
Its simple to do, and after you are done you can add them to custom vendors.
What you need to have is the Ascent Database Editor
Now that you have ADE open it and login to your SQL database where ITEMS are in. Now that u have access to the database, on ADE go to the Items Tab.
Once u have selected the Items tab, Click on the CHOOSE ITEM button. You should see a small window open where it lets you search for an item. You can also enter an items ID.
On the new window, What you want to enter in the ID section is the ID number 17413 which is Codex: Prayer of Fortitude
Now that that is open, you can modify the the:
-Entry ID (this is the Item number, make sure u change it to a number that is not yet taken)
-ITEM NAME (name of the book, ie: TAME BEAST or Deffensive Stance)
-Buy and Sell Price
-The type of CLASS (warrior, priest etc) that will be able to Use the item, and most importantly, the Spell it will cast/teach.
-And other stuff...
In this case I will want to make this Spell book teach a warrior (the player)
Defensive Stance. You should use THOTTBOT to search for the spell that teaches the warrior Defensive Stance.
NOTICE that if you go to the page linked here, you can see that this spell is not the actual DEFENSIVE STANCE but the spell which teaches the targeted person DEFENSIVE STANCE. This is very important that you make sure its not the actual Stance (or spell), but the spell that teaches the stance (or spell) or else the Book will only make the player go into Defensive stance, and not learn it.
Once u have the spell ID, replace the one Codex: Prayer of Fortitude has in the Spells tab. In this case since the spell i want to use to teach the player DEFENSIVE STANCE is 1612 thats what i want replace it with.
Now, just press UPDATE, and you have created a SPELL BOOK that teaches the spell.
Now you can add the item to Vendors .. this worked for me and made it easier for palyers to learn missing spells.
**Sorry for any confusions.. its late at night.. 3:20 am..., i will try to UPDATE it with pictures and more detail or if theres an easier way please post it.**
+Rep ??for trying...