Interesting. Here's more context for that, from Luke 22:
He said to them,
"But now if you have a purse, take it,
and also a bag;
and if you don't have a sword,
sell your cloak and buy one.
It is written:
'And he was numbered with the transgressors';
and I tell you that this must be fulfilled in me.
Yes, what is written about me
is reaching its fulfillment."
The disciples said,
"See, Lord, here are two swords."
"That is enough," he replied.
Please notice that: (1) He is consciously fulfilling the prophecy that he would be "numbered with transgressors." and (2) He evidently does not mean this for defense via the sword, because if the latter were the case, two swords would not be 'enough.'
Very shortly later, in in the same chapter, the following occurs:
"When Jesus' followers saw what was going to happen,
they said,
"Lord, should we strike with our swords?"
And one of them struck the servant of the high priest,
cutting off his right ear.
But Jesus answered,
"No more of this!"
And he touched the man's ear and healed him.
I am not arguing for total nonresistance here: pacifism is not a requirement of Christian morality, and you can find Scriptures showing the just use of the sword elsewhere in the New Testament (Romans 13).
My point is that this verse from Luke 22 which you cited is evidently not a precept in favor of armed force. St. Peter, understandably, interpreted it that way: but Peter was disarmed by Christ.
Earlier - Luke 9:3, 10:4 - Christ commanded that his disciples take nothing. This was during His earthly ministry. However, with the coming of the fulfillment of the prophecy, Christ knew His followers, as missionaries, would need to carry their provisions with them, and they would be faced with adversity. In Luke 22, he changed his commands reflecting this reality. The swords were for self-defense - not defense of Jesus, as that would negate prophecy, but rather defense of the disciples themselves, who would have the world arrayed against them as they spread the Gospel.