In stories where my PCs have encountered the Greek pantheon, I've had success in making one or two if them actually meet the god or an avatar and bestow upon the player a quest. It's good enough as a story excuse and actually fits well enough into Greek myth.

For instance, if one worships particularly the goddess of the hearth, he or she could be tasked by that goddess with building a better fireplace or finding eternal coals or something related to that domain.

As for rewards, I found making combat - enhancing weapons to be useful, but just as important were armor pieces with odd quirks and people trying to steal them. It adds mystique and realism, since if something is good, it's in demand. I always had fun making the weapons upgradeable.

Also, consider some of the best weapons to simply be steel weapons, as Golden Age weapons would be bronze, and rather weak comparatively. Same for armor - how easy would of be for medieval armor, over a thousand years of technological increase later, to stop arrows or blows. I would allow very good smiths, for instance, to discover iron then the steel making process.

I would suggest staying away from the well known mythic objects and monsters to forge your own legends, but that's just my experience.

Weapons in Greek myth were very ornate and had immense detail in the description, so I would always have fun making them depict gore or erotica, usually to a ridiculous and laughable degree.

As for long arcs - I always had fun with giant wars and ludicrous reasons for the fueds starting them. And revolutions! I once played in a campaign that implemented Fame and Glory as rewards like XP which influenced social rolls and incentivized madness or melodrama. That was fun, though it ended up rewarding the hams and good role players more than those who only liked battling.

I always wanted to do a campaign with Greek and Roman gods making their worshippers do battle, or turning out to be the same and manipulating them regardless.

Good luck!