Zelda Phantom Hourglass - Does anyone know how to defeat the phantoms guarding the door on route to trying to defeat Bellum

you kill them by attacking their backs with the phantom sword

~icesteak's addition~ also, if u set ur spirit power to ciela, or spirit of courage, u can shoot shock waves. if u dont wanna get close to the phantoms, u can just aim a shock wave at their backs. works just as good!