Have you entered Khrysalis? There is a level requirement but you also need to have the quest to enter Khrysalis before you get it. It's part of the main storyline I thought, so should be hard to miss? Link detailing spells by school.
There is no spell quest for King Artorius spells. You get it at the beginning of Khrysalis. Duncan Lvl 95 Duncan Lvl 50
Actually there is a quest. It is called "Letters of Light". You have to be at least level 85 and completed Azteca before getting it. My life wizard is level 90 and has had King Artorius for a while.
I just recently actually ENTERED Khrysalis long enough to get past the first 2 battles and enter the Bastion. I have been using this wizard and the rest from my main account to aid those on my 2nd account to get them out of the first arc and one that is currently over half way through AZ at level 88 Fire. The Fire will get that quest as soon as she finishes AZ.
I am aware there is nothing that states it as a Spell quest but if you check this link, you will find that the spell is a part of the rewards. "Letters of Light" is a main storyline quest.
