Goddesses are powerful companions who assist you in battle.
You will meet your first goddess, Leceiras, at some point in the main quest. Subsequent goddesses become available at different levels. Use Silver and that particular goddess's tear to unlock them!
Each goddess has their own unique Artifact.
Use Artifact Shards to upgrade artifacts.
If you fail to upgrade an artifact to L2 within seven days, it will become locked again.
After you upgrade the artifact to L2, it is yours forever.
Artifacts will upgrade the corresponding goddess' stats significantly.
There are seven genus of Goddess: Mystic, Fey, Celestial, Divinity, Primeval, Skyqueen, and Highqueen.
Extol your goddess to bring her to a higher genus. By increasing genus, your goddess will have more powerful skills and higher stats.
You'll need Silver and special materials to extol your goddess, but you can Extol for free 3 times a day.