Albert Barnes Commentary Ecclesiastes 7:12

"For wisdom is a defence, even as money is a defence; but the excellency of knowledge is, that wisdom preserveth the life of him that hath it." — Ecclesiastes 7:12 (ASV)

Wisdom is a defense ... - See the margin and (Psalms 121:5), that is, he who is defended from adversity by his wisdom is in as good a position as he who is defended by his riches.

Excellency - literally, Profit.

Giveth life to - literally, “Causes to live,” “makes alive” (Proverbs 3:18); the deeper meaning of which is elicited by comparing these words with (John 6:63); (Matthew 4:4).