“Charm is deceptive, and beauty is fleeting; but a woman who fears the LORD is to be praised.” The book is sandwiched with commendation for those who fear the Lord (1.7; 31.30). The values of this world, here symbolized by charm and beauty, are all but a vapor. Our Warrior Woman of Prov. 31 can be praised for dozens of different virtues, but the fear of the Lord is the capstone of them all.
People in general, and men specifically, are typically attracted to superficial attributes like charm and beauty. Charm, however, may hide a nasty personality, and beauty is meaningless unless it is also accompanied by godliness (Prov. 11.22).
The meaninglessness of physical beauty derives from its relative brevity. But godliness lasts forever.
This doesn’t mean a noble woman is necessarily abrasive and ugly; it simply contrasts these relatively worthless traits (charm and beauty) with what is truly important: the fear of the Lord. This is true of all people, male and female, but here is a reminder that a woman who deserves to be called noble is motivated by a proper relationship with her God.