"She girds herself with strength and makes her arms strong"
This is the Hebrew word chagar, which means to gird, to gird on, or gird oneself. The idea is that this woman is not frail but has strength through her core muscles. She is not a lightweight but keeps herself in shape to do real hard work. The strength that is mentioned first as girding herself with strength would refer to that which is around the middle of her body. This would be thighs, stomach, back – all the middle-of-the-body muscles.
The proverb does not make this contrast directly, but this kind of woman is in direct contrast to the mistress who does not want to be strong but to be dependent, frail, fragile, dainty, and beautiful. The virtuous wife has a whole different kind of beauty. It is functional beauty. The virtuous woman is not a doll that is put up on the shelf and only played with occasionally. The virtuous wife is a partner who can really team with her husband to build a stable and fruitful family.
God is very insightful in telling young men not to marry some fancy, unusable mistress; but instead you will be more blessed and more satisfied with a real woman who can partner with you in building your life to its maximum level.
Unfortunately in our modern era many men are only looking for a pretty face; and they do not understand the immense amount of work, diligence, and strength necessary for building a real life. There is nothing wrong with marrying a beautiful woman; but if that is all she is, then she is not the picture described here in God's Word as a virtuous wife. You will be disappointed regularly by what she cannot do if you only married her for her beauty and not her virtue with beauty thrown in.
and makes her arms strong
This virtuous woman is not afraid to be strong. Again this is in contrast to the mistress who is trying to get by on beauty and frailty. A husband and family need his wife to be strong to accomplish the various tasks that are necessary even in a modern context. The word armsis the Hebrew word zeroa, which means arms, shoulder. It is the upper part of the body including the shoulder and the arms.
This is not advocating a weightlifting program for women who want to be godly, but it is a focus for women who want to be pleasing to God and maximum benefit to their family. Frailty is out and strength is in.
When God is describing the ideal woman to pick as a wife for the young man who is out looking, He describes a different kind of woman that many men describe in their mind. God's woman is real and sacrificial and strong and competent. He says that this kind of woman will make a significant difference in your life and will bring about blessings and joy. The pretty face will not end up this same way. Virtue is working moral excellence and strength.