I have previously written an article about 1 Peter 3:7, the Bible verse that includes the phrase “a weaker vessel” [here]. Since writing this article, however, I’ve come across a few references in Greek papyri where women are called “weak”. In these papyri, women use the adjective for themselves hoping to elicit pity, or hoping to ingratiate themselves, while seeking justice from men. A.L. Connolly comments on several of these legal petitions and notes that appealing to a woman’s frailty (asthenēs) “had become commonplace in the rhetoric of petitions.”
Peter calls wives “weaker vessels” because he wants husbands, not necessarily to pity them, but to be more understanding with their wives who were, with few exceptions, disadvantaged economically, legally, and politically in the first century. However, cognates of the Greek word that Peter uses in 1 Peter 3:7 (e.g. asthenēs) are used elsewhere in the New Testament to mean sick and infirm, so physical weakness may have been what Peter had in mind.
Interestingly, Paul (who readily admitted to his own weaknesses) used cognates of asthenēs several times in his letters. He used them eleven times in First Corinthians, including 1 Corinthians 1:27b where he wrote, “God chose what is weak in the world to shame the strong.” Paul used the comparative adjective of asthenēs in 1 Corinthians 12:22 where he wrote, “the members of the body that seem to be weaker are indispensable.” Physical weakness is not a disadvantage in the body of Christ, and it need not be a disadvantage in marriage.
Peter used the comparative adjective of asthenēs in 1 Peter 3:7. Both Peter and Paul do not use the word “weaker” to insult or diminish anyone. In fact, they do the opposite. Like the women seeking justice, Peter uses the word “weaker” for its rhetorical effect, and he juxtaposes the phrase “weaker vessel” with the phrase “bestowing honour”.
It was not unusual to hear women being called “weak” or “weaker” in the first century. On the other hand, many would have been astonished to hear Peter tell husbands to honour their wives. Moreover, Peter gives the reason why husbands should honour their wives: because a Christian couple are co-heirs of “God’s gift of new life” (1 Peter 3:7 NLT). Being co-heirs is a strong basis for mutuality and equality in marriage.
I’m not bothered that Peter called wives “weaker”, considering it was part of the rhetoric of petitions. Rather, I’m delighted that he appealed to husbands to treat their wives with honour and understanding, and acknowledge them as co-heirs. It seems Peter was advocating for gender justice in marriage.
 “30. ‘The Weaker Sex'”, G.H.R. Horsley with A.L. Connolly, New Documents Illustrating Early Christianity: A Review of the Greek Inscriptions and Papyri in 1979, Volume 4 (The Ancient History Documentary Research Centre, Macquarie University, 1987) pp.131-133, 132.
 Apart from wives, Peter also writes that the Christians in Asia Minor should honour the emperor ( 1 Peter 2:17).
Submission and Respect from Wives in 1 Peter 3:1-6
Submission and Respect from Husbands in 1 Peter 3:7-8
Fear or Respect in Christian Marriage?
Equality and Unity in Ministry in 1 Corinthians 12
Protecting the Weaker Sex