Two hundred Romans, and no one’s got a pen? Never mind!“
He slung his M16 onto his back and pulled out a hand grenade. There were many screaming Romans. Then the hand grenade morphed into a ballpoint pen, and Mars began to write.
Frank looked at Percy with wide eyes. He mouthed: Can your sword do grenade form?
Percy mouthed back, No. Shut up.
Heroes of Olympus (The Son of Neptune)