This violates Christ's command to buy a sword!
The Crusaders were Christians and they owned weapons and many were martyred.
The Crusaders were murderers, rapists, and pillagers of Jews, Muslims, and fellow Christians.
Revelation 22
14 Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.
15 For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie.
Jesus said 2 swords were enough, not for defensive combat against the Roman troops coming to arrest Him, for that would be woefully insufficient.
Plus, Jesus said His kingdom was not of this world, so His servants would not fight.
The 2 swords were just to make the Romans reckon Him among the transgressors.
Luke 22
36 Then said he unto them, 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.
37 For I say unto you, that this that is written must yet be accomplished in me, And he was reckoned among the transgressors: for the things concerning me have an end.
38 And they said, Lord, behold, here are two swords. And he said unto them, It is enough.
John 18:36
Jesus answered, My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: but now is my kingdom not from hence.