Orientation in regards to gravity and vectors could also play a role, a spell usually has a direction in the case of projectile spells.
More complex shapes also need time to be formed as well, bringing a power VS speed into the meta on which spell to use.
Consider also presenting it as sacred...
I just want to leave the following wisdom I heard somewhere else: "In regards to copyright, if you feel like you have to ask whether you can do that, you most likely can't do that." This should also apply to plagiarism.