Which mythological artifact's 'product launch' included a competition where multiple gods showcased their gifts to win consumer preference in ancient Athens?

Throughout mythological tales across cultures, certain divine or magical artifacts were 'launched' into the world with great fanfare and changed the course of legends. These mythical products often came with extraordinary marketing campaigns (prophecies), targeted specific customer needs (hero quests), and sometimes even had recalls when they proved too powerful! Test your knowledge of how these legendary items were introduced to their mythological markets.

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Athena's olive tree gift, which competed against Poseidon's salt water spring
Thor's hammer Mjölnir, which was presented in a contest against Loki's spear
The Golden Fleece, which was unveiled during a festival honoring Zeus
Excalibur, which was compared to other magical swords in a royal tournament