What is the significance of “sell your cloak and buy a sword?” Simply, Christ directed what He said in Luke 22:36 to a specific audience, within a certain context, for a temporary purpose fulfilled when He was arrested.
Ed: This article was made when I was a Protestant and upon greater learning and reflection my thoughts may have evolved.
Orthodox Christian Theology 
He doesn’t say “sell everything you got and buy 2 swords with it.” He sells “Let him who has no sword sell his coat and buy one.” And then THEY say to him “Lord here are 2 swords.” So he didn’t tell them to buy 2. Now here is the problem. It is being played off in the passage as if this was done to fulfill the prophecy “that he may be counted among the transgressors.” Yet, a different event is identified in a different gospel as fulfilling that prophecy, namely him being crucified between two thieves. How does having swords make the disciples transgressors? IT DOESN’T. Being being crucified between 2 thieves makes Christ counted among the transgressors. Furthermore, its not the disciples but JESUS that needs to be counted among the transgressors to be the fulfillment of the prophecy!
So there is very much a problem with the passage. Furthermore, notice how the passage starts, i.e. verse 35 “When I sent you without purse, and scrip, and shoes, lacked ye any thing? And they said, Nothing.” So everything was fine last time he sent them out, but verse 36 ” But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one.” Up to this point its clear that the counsel to sell your coat and buy a sword if because the times have changed and become more dangerous, when he sent them out before everything was fine, “but now…” Hmmmm.
But now the next verse comes in “For I say unto you, that this that is written must yet be accomplished….” Ok, considering that verses 35 and 36 are CRYSTAL CLEAR that the reason for buying the swords is a change in climate, that the times are more dangerous, its clear the real reason is for self-defence. YET here is now the claim its for prophecy fulfillment, a prophecy fulfillment better fulfilled by Jesus being crucified between two thieves (that HE may be numbered) than by the disciples having swords (that THEY may be numbered?) as I already discussed. So if you think LOGICALLY it seems like verse 37 playing this off as about prophecy fulfillment and verse 38 “here are 2 swords. it is enough” are interpolations intended to CHANGE the original intent and REMOVE Jesus’ authorization of self-defence. Otherwise, what are we to believe, that Mark 15:27-28 is wrong about it being Jesus’ being crucified between 2 theives that fulfills the OT prophecy? and that Luke 22:37’s prophecy claim is the one that really fulfills the prophecy (Even though then it would be the disciples and not Jesus that fulfilled the prophecy) despite Luke 22:35-36 CLEARLY being about self-defence before the senseless interjection of verse 37 which is an obvious interpolation?