The wrath of a king is as messengers of death. In a despotic monarchy the death of an offender follows quickly on the offence. Anger the king, and punishment is at hand; instruments are always ready who will carry out the sentence, and that before time is given for reconsideration.
The murder of Thomas a Becket will occur as an illustration (comp. Esther 7:8, etc). The LXX. translates, "The king's wrath is a messenger of death," taking the plural as put by enallage for the singular; but possibly the plural may intimate the many agents who are prepared to perform the ruler's behests, and the various means which he possesses for punishing offenders.
This first clause implies, without expressly saying, that, such being the case, none but a fool will excite the monarch's resentment (comp. Ecclesiastes 8:4); then the second clause comes in naturally.
But a wise man will pacify it. He will take care not to provoke that anger which gluts its resentment so quickly and so fatally (Proverbs 19:12; Proverbs 20:2). Septuagint, "A wise man will appease him," the king; as Jacob propitiated Esau by the present which he sent forward (Genesis 32:20, Genesis 32:21).