1. Augustine's argument for why Peter was reprimanded by Christ for defending his savior in the garden is that Christ did not give Peter the authority to use the sword. Matthew 10 gives us the context for what authority Christ gave his disciples, and it has no inclusion of violence. They had the authority to drive out demons, heal, lodge with those who were hospitable, and share the gospel of the Kingdom. The use of the sword is not included. If you want to use an Augustinian line of reasoning to justify violence based on authoritative command, you can't use this passage.
2. In this same passage, preceding Christ's reference to the sword, he tells his disciples that they will be sheep among wolves, and they are to remain as innocent as doves. He proceeds to tell them how they'll be beaten. This hardly seems that Jesus is advocating violence in response to opposition.
3. Jesus does give one specific response his disciples are to have to persecution. They are to flee. Jesus just told them that they would be put to death due to their family members betrayal. We're not just talking about how to respond to a beating, but to imminent death. Jesus tells his disciples to run away.
4. The verses immediately preceding Christ's sword comment are the familiar ones about not fearing what men can do to our bodies, God has numbered our hairs, we're worth more than sparrows, etc. This is not at all the language of the disciples bearing the sword, but rather the disciples receiving the sword.
When we come to the verse where Christ talks about the sword, then, the context is that the disciples have authority to help others and spread good news, they will be persecuted and betrayed yet are to remain innocent through that, and they should try to escape evil, but if they don't, remember that the Spirit will help them and God cares for them no matter what. The verse about the sword, then, is metaphorical in the sense that Christ divides a family like a sword (reminds me of the dividing language in Hebrews 4:12), but it is also literal in the sense that a disciple's own family may put them to the sword.
5. Jesus goes on to say that disciples are to love Christ more than their family, and here tells the disciples what that love looks like. It doesn't look like self defense against persecution, it looks like taking up their cross and following Christ. Because "whoever finds their life will lose it, and whoever loses their life for my sake will find it." This passage, then, is not at all about the preservation of one's physical life, but rather the loss of it in light of the eternal.