[@KatherinWinter]

Alright, so, ritual spells. Drawing from standard fantasy rules; ritual spells are generally performed for the purposes of casting magic which is for one reason or another outside the capacity of the casters. In the case of this ritual, Argus is treated as a material component like the white sand used to form the ritual circle, or the red candles used by some satanists and wiccans. Technically speaking Richard is the one doing the actual casting; Argus is simply acting as a conduit which targets the spell in a particular way.

He's the son of a military leader from a somewhat feudalistic society; sons are expected to take their father's place or at least serve in the same line of work. He was heavily educated in the capabilities of the magic used by Djinn and their allies with the expectation of eventually becoming a field commander or general.

He knows the spell because it was part of his childhood military education.