A wicked messenger falleth into mischief: but a faithful ambassador is health.
A wicked messenger falleth into mischief. A messenger who does not execute his 'embassy' 'faithfully,' "falleth into" the penalty of his faithlessness.
But a faithful ambassador (is) health - alike to himself and to those by whom he is sent. Bad rulers and their bad ministers or agents are both accursed by God (cf. 1 Samuel 22:17-18, with Psalms 52:1-9, title; 2 Kings 1:9-14).