@stanfoo : the thing is you can modify an other spellbook from your own inventory and change is "stats" name to "transform" it from the old one to the one you want
the problem is, items ID can't always completely guessed, so I hope for you you'll find one, or somebody will find one and give you the stats name.

edit: I found a scroll with this "SCROLL_CreateGreaterUndead"
give a try to one of your skillbook and modify it like SKILLBOOK_CreateGreaterUndead
can't assure it will do, but at least it is a real ingame value.
if it doesn't, just craft one from the scroll ^^

@Gotcha! : yes damages (armor points, sight malus, elem res...) are level related, AND item related : I mean if you have an old plate armor vs a new plate armor, at the same level, the new plate armor will have some more defense.