I submit that it is impossible to be the bringer of Truth and the Bringer of punishment, because these two things are mutually exclusive.
If your concern yourself with Truth, then you cannot concern yourself with FORCE, which is contrary to Truth. Speaking Truth to people is to accept that individuals possess their own Will, Moral Agency, and Self. Therefore, you can only seek to convince them, not to force them.
Punishment, forced coercion, threats, violence, destruction, death, hell…these things are the vestiges and vagaries of falsehood. Of lies, deception, manipulation, artifice, and deceit. Therefore, let evil liars employ these things to their own damnation.
You, as a rational being, as a messenger of Truth and Goodness, honesty and reason, should concern yourself with dialog, discussion, and categorical voluntarism.