The events in the Upper Room ends with a warning. Jesus had previously told the disciples to go out without money, sandals, etc. to proclaim the Gospel. But now, He says, they are to go out ready for anything—bring everything and even buy a sword. But, they missed the point and produced "two" swords. Jesus says, “enough,” and I do not think He is referring to their two swords. Rather, I think Jesus is saying, “Enough of this." You’ve missed the point, which is "the strategy must change." A year or two ago I was popular. You went in My name and were received gladly. In a short period of time, I will be killed and you will have no popularity. You are to prepare for those days.

Unlike Hendriksen I do believe it is an actual call to arms though. We need to note that protection is not always against another human being. The disciples would now be traveling with the Gospel and all kinds of treacheries lie in wait--wild animals, etc. Swords are also used for hunting and cutting of beef, etc on the highway. In addition, as Christians we are still allowed to defend (intimidation, at least) ourselves against "hostilities," (robbers, etc) which is different than hostility against the Kingdom message.

The usage of the swords though I do not believe was for physical protection against the aggressors of the Kingdom message as we see all of the disciples martyred (save John who was exiled) and not a hint of physical resistance, except when Peter blew it. I somewhat agree with Nolland here (but not with the entirely of his commentary to be sure).

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The directive to buy a sword deserves a measure of separate consideration. Lined up as it is with purse, bag, and sandals, we can eliminate at once any idea that zealot sympathies are coming to expression with the commendation of the sword. The sword is thought of as part of the equipment required for the self-sufficiency of any traveller in the Roman world. Similarly there can be no thought that the swords might be used to make a defense of Jesus (as Gillmann, LS 9 [1982] 142–53) or might be for use in an anticipated eschatological armed struggle (as Bartsch, NTS 20 [1973–74] 190–203).

Nolland, John. Vol. 35C, Word Biblical Commentary : Luke 18:35-24:53. Word Biblical Commentary, Page 1076. Dallas: Word, Incorporated, 2002.

Reformed and Always Reforming,