The WTS has had varying interpretations of this scripture, many of them insulting: 1) that women are weak emotionally 2) that their menstrual cycle renders them weak mentally, emotionally, and physically 3) that they are inferior mentally.
The most recent statement on this shows an adjustment. But remember that Rutherford was the one who was reported to have said:
In 1941, the JW’s believed that the end of the world would come in a matter of months. In view of the closeness of the Millennium, Judge Rutherford advised JW’s not to get married, saying, "Why, then, should a man who has the prospect before him of being of the great multitude now tie himself up to a stack of bones and hank of hair?"
http://www.jehovahs-witness.net/watchtower/scandals/104671/1/Judge-Rutherford-on-radio-God-says-Quit-making-Jackasses-of-yourselves
*** w05 3/1 pp. 17-18 Wise Guidance for Married Couples ***
"A Weaker Vessel" in What Way?
8 In saying that the woman is "a weaker vessel," Peter did not mean that women are weaker than men intellectually or spiritually. True, many Christian men have privileges in the congregation that women do not expect to have, and in the family women are subject to their husbands. (1 Corinthians 14:35; 1 Timothy 2:12) Nevertheless, the same faith, endurance, and high moral standards are required of all, men and women. And as Peter said, both husband and wife are "heirs . . . of the undeserved favor of life." As far as salvation is concerned, they have equal standing before Jehovah God. (Galatians 3:28) Peter was writing to anointed Christians of the first century. Hence, his words reminded Christian husbands that as "joint heirs with Christ," they and their wives had the same heavenly hope. (Romans 8:17) One day, both would serve as priests and kings in God’s heavenly Kingdom!—Revelation 5:10.
9 Anointed Christian wives were in no way inferior to their anointed Christian husbands. And in principle, the same is true of those with an earthly hope. Both men and women of the "great crowd" wash their robes and make them white in the blood of the Lamb. Both men and women share "day and night" in the worldwide shout of praise to Jehovah. (Revelation 7:9, 10, 14, 15) Both men and women look forward to enjoying "the glorious freedom of the children of God," when they will delight in "the real life." (Romans 8:21; 1 Timothy 6:19) Whether of the anointed or of the other sheep, all Christians serve Jehovah together as "one flock" under "one shepherd." (John 10:16) What a compelling reason for a Christian husband and wife to show due honor to each other!
10 In what way, then, are women ‘weaker vessels’? Perhaps Peter was referring to the fact that, on average, women are smaller and have less physical strength than men. In addition, in our imperfect state, the wonderful privilege of bearing children exacts a physical toll. Women of childbearing age may be subject to physical discomforts on a regular basis. They certainly need special care and consideration when experiencing such discomforts or enduring the exhausting trials of being pregnant and giving birth. A husband who assigns honor to his wife, recognizing the support that she needs, will contribute greatly to the success of the marriage.
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Past statements that were insulting:
*** w51 5/1 p. 279 Making a Success of Marriage ***Consider the biological constitution of the female, her limitations, her cycles, her vicissitudes, which greatly affect her mental processes, disposition and temperament. God does not overlook these feminine restrictions; neither should husbands. (Lev. 18:19; 20:18)
*** w80 5/15 p. 8 Why "Be in Subjection"? ***Because of her vicissitudes or cyclic emotional nature her husband is required to show patience, kindness, consideration..—Lev. 18:19; 20:18; 1 Pet. 3:7-9,