My interpretation of this verse is that Jesus was giving the disciples new instructions for their journey after his departure. In the past, they needed nothing, but in the future, they would need to carry money and provisions, but why the sword? The Roman short sword seems to be in mind here. Jesus counseled his disciples to turn the other cheek or to carry a pack 2 stadia instead of one. Why? Because a Roman soldier could legally strike you once or compel you to carry his pack 1 stadia. Jesus was saying in effect, not to resist legitimate governmental authority no matter how unjust, but to prove God’s love in the Good News by going the extra mile and surprising your enemy by your response.
However, there this counsel may not have been meant for dealing with brigands and bandits, who might now accost the gospel missionaries on the road between cities. This type of robbery was common, but represented complete lawlessness, and the point of the attack had nothing to do with the witness of the gospel or as response to the gospel. In other words, it was not persecution for the gospel’s sake but mere lawlessness. Was Jesus instructing them to be ready to protect themselves against such common injustice? Perhaps so.

My research into Roman law is that while slaves, who were not body guards, were not allowed to carry weapons, free people were required to provide their own swords for service in times of crisis. Since the common person in Roman territories would have needed protection on their journeys, it seems that carrying swords for this purpose was allowed. The following is from the time of Justinian, dating back perhaps to Cicero, but the codification of Roman law allowing self defense.

I. SELF DEFENSE
Roman law was very protective of the individual’s right to defend himself and his property from violence, whether offered by a thief on a darkened highway or a soldier in search of plunder.viii A provision attributed to the late fourth century A.D. reads:
We grant to all persons the unrestricted power to defend themselves (liberam resistendi cunctis tribuimus facultatem), so that it is proper to subject anyone, whether a private person or a soldier, who trespasses upon fields at night in search of plunder, or lays by busy roads plotting to assault passers-by, to immediate punishment in accordance with the authority granted to all (permissa cuicumque licentia dignus ilico supplicio subiugetur). Let him suffer the death which he threatened and incur that which he intended (Codex Justinianus (“CJ”) 3.27.1).
The legislator then explains the rationale for this provision, stating, “For it is better to meet the danger at the time, than to obtain legal redress (vindicare) after one’s death.” And he concludes:
We therefore permit you to seek your own revenge (ultionem) and we join to this decree those situations which a legal judgment would be too late to remedy (quod serum est punire iudicio). Thus, let no one shrink from facing (parcat) a soldier, whom it is fitting to challenge with a weapon (telo), just as it is fitting to challenge a thief (A.D. 391).ix
This provision recognizes not only an individual’s right to self defense, but explicitly permits the private use of a weapon (telum) for the purpose of countering an assailant as well.
http://www.secondamendmentlibrary.com/JFPP%20WEBSITE%20FILES/16/The%20Roman%20Legal%20Treatment%20of%20Self%20Defense%20and%20the%20Private%20Possession%20of%20Weapons%20in%20the%20Codex%20Justinianus.pdf

Commentary by jefferis peterson
Posted on: 6/12/2010 13:46 pm

If a common person carrying a sword in Roman times was “illegal,” or simply “inappropriate,” why did the disciples have two swords at the last supper? Shouldn’t Jesus have told them to get RID of them and NOT to carry them, if swords were wrong to have? Shouldn’t Peter also have been arrested at the betrayal for having such a weapon on him? Actually, it sounds more like it was fairly routine for normal people to carry weapons then.

Using our(rather recent)stigma against personal weapons, we run all over and around the Luke 22 reference to “buying a sword” by trying to make it a spiritual sword only. Why not also make the other parts of the provisions spiritual only? The spiritual connotation justly can be applied, but the disciples clearly understood that He meant PHYSICAL items, and he did not correct their (mis?)understanding. Was He trying to mislead them? If so, He succeeded wildly. Why didn’t he clarify his meaning even a little?

As for Peter’s use of a sword at the betrayal, Jesus knew there was nothing to be gained by fighting to save him. In fact, it could have thwarted God’s plan for him to die.

We must see the words for what they ARE, not for what we WISH they were. Let us not try to read back our 21st century ideas and social stigmas into 1st century culture and society. All it will do is force strange interpretations into our understanding of scripture.

Commentary by Joe Lochamy
Posted on: 5/26/2009 13:49 pm

Thanks Mr. Celiktemur

Commentary by Jason W. Elder
Posted on: 5/4/2009 23:04 pm

Jason,
Although this is not a direct answer to your question, it seems that those who carried swords in those days were regarded as potential criminals or even bandits. So I would assume this was not regular practice, at least for those who cared about a good reputation.

Commentary by Bahadır Celiktemur
Posted on: 5/4/2009 12:31 pm

Does anyone know if the Romans allowed common people to carry swords?

Commentary by Jason W. Elder
Posted on: 4/22/2009 17:56 pm