Athena was a huge help in Hades, but doesn't show up to offer her Boons in the sequel. There's a story reason given, though, as Hephaestus explains that she's testing weapons and armour.

One of central Athens' best preserved ruins is the Temple of Hephaestus. Nestled within Ancient Agora, this site was built between 460 and 420 B.C. and once served as a Christian church.