The term illusionist, I am certain, stems from my kind's ability to create illusions in the mind of those we feed upon. It is the way the soul is drawn out of the body; our illusions make portions of the soul vulnerable enough to be drawn out.

As for "soul", I am uncertain, although I believe it was the result of folklore regarding my kind. While I do not feed on anything save for Power, other illusionists choose Potency to feast upon. Should a creature survive having their soul taken out in its entirety, what is left appears as little more than an empty husk with no thoughts or desires. They believed this to be akin to having no soul, thus, the illusionist must have removed it.