1 tn The form נָאוֶה (na’veh) is an adjective meaning “seemly; comely” in the older English versions like KJV, ASV, “fitting” in more recent ones (e.g., NASB, NIV, NRSV). The verbal root נוֹה only occurs in the Pilel stem; but it also has the basic meaning of “being fitting; being comely.” In this sentence the form is a predicate adjective.
2 sn The verse is simply observing two things that are misfits. It is not concerned with a fool who changes and can handle wealth, or a servant who changes to become a nobleman. It is focused on things that are incongruous.
3 sn In the ancient world the prince would be trained for his rule (hence, one of the original purposes of Proverbs). A slave ruling over princes would be arrogant and cruel, or foolish and unwise. For other unbearable things, e.g., 11:22; 17:7; 26:1; and 30:21-23.