With a bit on mental gymnastics it is possible to have Athena as an Ancestor, by way of Erichthonius. when she wiped away some of Hephaestus
"Stuff" perhaps it absorbed some of her divine essence. the character would have to be a Hero unless they had other divine heritage, but they can also claim Hephaestus as a Patriarch and Gaia as a surrogate Matriarch.
[Does a little homework on Erichthonius...] I would put that as sketchy source of divinity. But, some articles list her as a patron for Erichthonius and I could see a child coming from that relationship.
Well till Mortals looked in the Box she was going to rise him as her full and true Son, so he must have got part of her divine essence mixed in there, He was a "Mortal" King but his descendants can claim Divine Heritage from potentially three Sources, and unless they had a closer Divine Ancestor they would be "Heroes" not Gods.