During his first adventure, Percy Jackson would have died without his sword, Riptide. Known by its Greek name, Anaklusmos, Chiron gave the weapon to the son of Poseidon. Heracles and Zoë Nightshade have also wielded it.
The weapon takes the form of a standard ballpoint pen. However, if the cap is removed, it will grow and form into Riptide. The lid has the shape of a trident etched as a sign that is likely a gift from Percy’s father, Poseidon.
Riptide will return to the user if lost. So, if Percy were to drop it off the bridge when he fought Echidna during his first adventure with Annabeth and Grover, it would return to his pocket after a while.
Like Annabeth’s knife, baseball cap, and Grover’s panpipes, Percy doesn’t go anywhere without Riptide. Since it is cerebral bronze, it will pass harmlessly through mortals if they are attacked. Fun note, it is established after the first Percy Jackson book that Percy sleeps with Riptide under his pillow. Given he is constantly the target of monster attacks, it makes the most sense. Also, it gives him peace of mind that he can keep himself and his mother, Sally, safe if needed.
This would later extend to his second stepfather, Paul and little sister, Estelle, once she was born.
Skills With Riptide Extend To Other Swords
Given that Percy is one of the most accomplished fighters Chiron has ever taught, his efficiency with Riptide seems to extend to any sword. This is always handy, given that he can use another if he doesn’t have his own on hand.