Percy was fighting like a whirlwind. In fact…he was a whirlwind. A miniature hurricane of water and ice vapor churned around him as he waded through the enemy, knocking Roman ghosts away, deflecting arrows and spears. Since when did he have that power?
He moved through the enemy lines, and even though he seemed to be leaving Frank undefended, the enemy was completely focused on Percy. Frank wasn’t sure why—then he saw Percy’s goal. One of the black vapory ghosts was wearing the lion’s-skin cape of a standard bearer and holding a pole with a golden eagle, icicles frozen to its wings. The legion’s standard.
Frank watched as Percy plowed through a line of legionnaires, scattering their shields with his personal cyclone. He knocked down the standard bearer and grabbed the eagle.
“You want it back?” he shouted at the ghosts. “Come and get it!”

The Son of Neptune, Chapter XLVI