C. F. Keil and Franz Delitzsch on Ecclesiastes 9:18

Ecc 9:18

The following proverb also leans on the history above narrated: “Better is wisdom than weapons of war; and one sinner destroyeth much good.” The above history has shown by way of example that wisdom accomplishes more than implements of war, כּלי ק = כּלי מל (Assyr. unut tahazi)Vid., Fried. Delitzsch’s Assyr. Stud. p. 129.i.e., than all the apparatus belonging to preparation for war. But the much good which a wise man is accomplishing or has accomplished, one sinner (חוטא)The Syr. (not the Targ.) had חטא before it, and thus realized it, which appears to correspond better with the parall. חכמה. by treachery or calumny may render vain, or may even destroy, through mere malicious pleasure in evil. This is a synthetic distich whose two parts may be interpreted independently. As wisdom accomplishes something great, so a single villain may have a far-reaching influence, viz., such as destroys much good.