C. F. Keil and Franz Delitzsch on Proverbs 20:28

Pro 20:28 28 Love and truth guard the king;      And he supports his throne by love.

We have not in the German [nor in the Eng.] language a couple of words that completely cover חסד ואמת; when they are used of God, we translate them by grace and truth [Gnade u. Wahrheit], Psa 40:12 (יצּרוּני); when of men, by love and truth [Liebe u. Treue], Pro 16:6; and when of the two-sided divine forces, by kindness and truth, Pro 3:3. Love and truth are the two good spirits that guard the king. If it is elsewhere said that the king’s throne is supported “with judgment and with justice,” Isa 9:6 [7]; here, on the other side, we see that the exercise of government must have love as its centre; he has not only to act on the line of right, שׁוּרת הדּין; but, as the later proverb says, in such a way, that within this circle his conduct is determined by the central motive of love. In this sense we give the king not only the title of Grossmächtigster [most high and mighty], but also that of “Allergnädigster” most gracious, for the king can and ought to exercise grace before other men; the virtue of condescension establishes his throne more than the might of greatness.