Oversized forks with the power balance other spells. Cal and Jake use the tridents to mitigate Medusa's magic in her alternate dimension so they can fight her Stonemen and retrieve the Fleece.
Hephaestus forged armor for Cal when he was a child to help mitigate his vulnerability. Despite the suit looking like colorful spandex(Cal's design,) it is impenetrable. Almost.
Maybe the most powerful totem in the world, the Golden Fleece works as a magic lamp for anyone who holds it. Zeus demands Cal and Jake retrieve the Fleece so he can find Hera(hiding as a mortal with no memories of her true origins.)
As Cal's power grew exponentially, Hades asked Zeus if they should create a way to hold him in check. Zeus, fearful of losing his throne, agreed and asked Hephaestus to create a sword capable of killing a God. Hephaestus used the blood of "The Four" and Charon's essense of death to create The Godslayer. The sword proved effective and eventually to Zeus fleeing the throne. Hades created a powerless doppleganger sword to battle Cal in Hell.
ORB OF TARTARUS
Zeus, Hera, Poseidon and Hades created a spherical prison to hold their filicidal parents, Chronos and Gaia, while seizing control of the Greeks. Zeus frequently talked to the Orb after its creation.
Cal, Athena and Hermes found Hephaestus and convinced him to create a sword capable of sending someone new to Tartarus. Hephaestus used the blood of the five children of Zeus and the Orb to create the Tartarus Sword. He made it the only thing capable of penetrating Cal's armor.