ALWAYS buy swords in pairs:

Luke 22:35
He said to them, "When I sent you forth without a money bag or a sack or sandals, were you in need of anything?" "No, nothing," they replied.
36
He said to them, 12 "But now one who has a money bag should take it, and likewise a sack, and one who does not have a sword should sell his cloak and buy one.
37
For I tell you that this scripture must be fulfilled in me, namely, 'He was counted among the wicked'; and indeed what is written about me is coming to fulfillment."
38
Then they said, "Lord, look, there are two swords here." But he replied, "It is enough!"