The ghosts weren't visible things to see, to ordinary eyes, though Zechs was unaware. The objects they'd use to strike, however, were. There's a flash of movement Zechs saw out of the corner of his eye, approaching Koumyou from the left and rear.

He didn't bother shouting a warning, using a burst of speed to move forward. Zechs intended to knock the older man away with a shoulder, and catch the supernaturally animated piece of debris - an abandoned, dull hunting knife - across his chest instead. Only a glancing blow for Zechs.

Preferable to being stabbed in the back.