numbered spell levels pre-D&D (comics history question)

[Kobold Stew]

I'm reading a 1968 Charlton Hercules comic, and Hera casts a "type six" spell (with the implication this is pretty powerful). There's no previous context in the series for this sort of talk -- is there something in pop culture? What previous fiction used numbered spell power-levels that this would make this the obvious way for a goddess to speak?

Thanks for any help!