"Understand, Wilhelm, that I can knock you out with a single touch if you try to mess with that shrine. I don't want to, but I will."

He's already done it to Geralt once in this experience, to save Steve, so he may as well for Wilhelm too. It would probably be kinder at this point, although he really does not want to use any actual force against the boy. Sometimes there are no real good choices in the pit. Only things they have to do to get through another day.

He releases Wilhelm from the pin and steps back but he is clearly watching him very closely in case of him acting in any way irrational. Istredd thinks it's either making him unconscious or allowing him some ability to communicate his feelings toward a dead sibling.

"Talk to him."