Long ago I had made a video about how Greek Mythology (more specifically the TitanClash) connects with One Piece, and how Oda ,I believe, has used it as part of the Ancient Weapons / Void Century. Furthermore, we have now learned about Sun God Nika.

SUN GOD

During the Titan Clash one of the Gods that helped Zeus was Apollo.
Before going further , for many centuries (until after Jesus birth) God Apollo and God Helios were thought to be the same God.
Helios is the Greek word for Sun. Helios : Ήλιος
God Apollo was the God of music, dance, light and Sun and some other things
Nika

During the Roman Empire, Constantine the Great was marching towards the Milvian Bridge to fight Maxentius. The night before the Battle he had a vision/dream, he saw a flaming Cross coming down from heaven and he heard Jesus saying “En toytw Nika” (Greek : Εν τούτω Νίκα , Latin : In hoc signo vinces) , translating as “win with this”. After this dream/vision , Constantine commanded all units to draw in the armor and shields the first two letters of Christ’s name, Chi & Ro. And if they would come victorious , he would become a christian himself.
In which religion did Constantine belong until then? He believed in God Helios.
Other important mentions

Big Moms Homies, except Napoleon , have a connnection with the Titan Clash.
Zeus: The Leader of the Olympians
Hera: Zeus’ official wife (he was a kinky God)
Prometheus: A Titan who stood with Zeus, and later gave the fire to Humans
Ancient Weapons.

Uranus: Either the Grandfather of Zeus or Zeus’ nickname
Pluton: Hades’ Nickname, the brother of Zeus, Ruler in the Kingdom of the Underworld
Poseidon: The third brother and Ruler in the Kingdom of the Seas
Theory

I don’t agree with the term “weapons” anymore. Shrahoshi may be Poseidon but a living Creature not a weapon.
Anyway, Oda has used “three” ancient Weapons, as the “Three” Brothers who ruled the Universe after winning in the Titan Clash.
But as in Mythology, they were not only “three”. I believe Sun God Nika , is connected to them and a very powerful individual. He may not be on the scale of Poseidon, in terms of power, still we could say the “fourth ancient weapon“.
*Theory by ThousandSunnyReview