Why would you have to buy a spiritual sword- God grants that for free.
When Jesus encounters the faithful centurion - an member of the foreign military no less- he doesn’t tell him to drop his sword and desert.
Later, when men came to arrest Jesus, Peter took out his sword and it was real enough to cut off a man’s ear. Peter hadn’t been smuggling the sword around all that time without Jesus knowing he had it, it was by all description an ordinary piece of equipment. No one was surprised by it, it just wasn’t the appropriate time to use it for Jesus still had to go through with his mission, which meant arrest and trial and death on the cross, and fighting to avoid arrest was pointless.
Jesus uses lots of parables piasa.
I’m going to read the passage again and see the context before I post further.
Take Care