If you're trying to get rid of Spell Slots, remove the Level:1 at the top of each spell, and replace it with Level: Cantrip.

I wouldn't mind a little detail about the Organization and what tattoos/abilities each would have.

Most of the abilities atm just exchange HP for equipment, which isn't too broken. I'd say any player could easily have these and not become OP.
I do question why they would need it, however. Why is this cult so low on weapons that it is easier to use magic to create them? More of a Lore question than mechanics.