So why would Jesus want us to sell the shirt off our back to buy a weapon?
One possibility is that in those times, a sword was not just for war, it was a tool for personal protection against the elements, etc. and almost all men carried them.
Also, having a sword and using it for war is not the same thing. In some cases, conflicts and even wars are prevented because the opponent is well armed and it is decided that the possible consequences are not worth the fight.
Because we value the right to bear arms does not necessarily mean that we believe in waging war.
There are probably other possibilities but we have no explanation from Jesus regarding what exactly that meant so you can believe what you want. The totality of Jesus' teachings lead me to believe he did not condone war.
Do you believe that Jesus is God? If so, then re-read my Post number 4. If you don't believe Jesus was God, then we should just agree to disagree.