Jamieson, Fausset and Brown on Ecclesiastes 10:11

11. A "serpent will bite" if "enchantment" is not used; "and a babbling calumniator is no better." Therefore, as one may escape a serpent by charms (Psa 58:4, 5), so one may escape the sting of a calumniator by discretion (Ec 10:12), [Holden]. Thus, "without enchantment" answers to "not whet the edge" (Ec 10:10), both expressing, figuratively, want of judgment. Maurer translates, "There is no gain to the enchanter" (Margin, "master of the tongue") from his enchantments, because the serpent bites before he can use them; hence the need of continual caution. Ec 10:8-10, caution in acting; Ec 10:11 and following verses, caution in speaking.