I can understand the developers. They were following the principle of "don't multiply what exists without a good reason." In the third game, there are many unused spells, especially in multiplayer. But the absence of a spell that is the opposite of "Grief" is still unclear to me. It could have slightly diversified the gameplay.
I used these spells... if I was a specialist in a particular school... it's still nice to immediately increase the Defense or Luck of all your units if you don't have artifacts that boost them.
+Defense and +Luck would be a good addition to light magic and would be boosted by the Master of Blessings.
-Defense and -Luck would be a good addition to dark magic and would be boosted by the Master of Curses.