To understand this larger passage, a good starting point is in verse 10: "For this reason a woman ought to have a symbol of authority upon her head, because of the angels."
When we read that Jesus tells his disciples to buy a sword, it can seem that he is encouraging violence. Yet when Peter does use a sword in the garden of Gethsemane, Jesus rebukes Peter and heals the man’s ear. So, whatever Jesus was up to in telling his followers to buy swords, he clearly didn’t intend for them to use them!
Romans 9:13 states, “Just as it is written: ‘Jacob I loved, but Esau I hated.’” Without background this is a disturbing verse! There are two pieces of contextual information that help us understand what Paul is saying.