Well, I finally got my concise anglo-saxon dictionary in the mail, and here are the sub-final results of my research into the root words of “wicca”:

wicca: m. wizard, magician, soothsayer, astrologer
(please keep in mind that this word is not just left for males because it’s masculine) (actual anglo-saxon root: wicga)

wicce: f. witch (found in AElfric and the Old English Glosses)

So Gardner wasn’t too far off, but that’s given that these words are recent additions to the anglo-saxon vocabulary (potential fix?) and have only been found in a couple places, which still leads me to be skeptical of whether or not they actually did exist. Now to go hunt down the texts they were found in, with the original language to do a translation.