He doesn't know how to prove it, is the thing. The copies of themselves are not someone else's poor attempt at impersonation. They are them, just perhaps crueller, more prone to turning all their hate inward. He looks on, helplessly, his palms spread wide so that Zhou Zishu can see he has no weapon.

"I don't know how, Ah-Xu." Frustrated, at his own ability, "I could tell you things that only I know but that won't help you, will it? That -" And he nods to the other Zhou Zishu, the angrier one, "That knows your secrets too, doesn't it?"

His gaze drops to the sword, "You could stab me, I'd let you? Then you'd know I wasn't anything else."