I recently finished my paper and presentation over Luke 22:35-38, which you can read in the below post. I settled down on one conclusion, although I think there exist two possible and strong interpretations.
Jesus is trying to prepare the disciples of the impending danger and hostility that they are about to face, because they will be viewed as transgressors for following Jesus. Although, this is not the best interp, I think that Luke may have had this in mind when writing his gospel to the gentile community which was receiving hostility from many different angles, Jewish Christians (not real harsh), Romans, and Jews (pretty harsh).
The disciples are betrayers of Jesus, and this question, answer device reveals their hearts. Jesus is quite ingenious in asking the disciples and then commanding them to get swords, because they reveal that they have already lost faith in his earlier commands from Luke 9 and 10 to take nothing with them on mission. The fact that they already have swords means that they are treacherous. This theme of treachery fits well with the 3 preceding pericopes which all fit together with similar elements and also form a farewell speech.
Why would this be important for first century followers of Jesus? These men who have following Jesus bettrayed him by preparing themselves for violence. As the times erupt with violence with teh destruciton of hte Temple, Christians will be forced into a hard place. The correct reaction is not violence, and Luke wants them to know this.
How badly we need this message. The correct reaction to violence is not violence, but rather a different way. The Christ way of the cross. Sounds unfamiliar, sounds unAmerican, but it sounds biblical. We as a Christian church need to pick up this devotion to Christ so that we can have the kinds of hearts that will not prepare for violence, but rather prepare for grace.