Who was the one that control Shalltear?

Slane theocracy controlled Shalltear Bloodfallen.

How was Shalltear Bloodfallen mind controlled?

As she launched the projectile right at Kaire, Cedran steps in-between them and attempts to block the attack with his shield. However, the javelin easily pierced through him and his shield, inflicting a severe injury on Kaire, effectively preventing her from completing the mind control.