Hi Levinas,
In the verses you quote, Jesus admits that he is changing his instructions. Whereas before, the disciple were relatively welcome, from now on, they will meet with a hostile environment, signified by the haversack (to carry your own food) and the sword (to get your food by violence, if necessary). Jesus’ message is for the disciples to get ready for hard times. Obviously the disciples did not understand him. They take him literally and come up with two swords. Jesus chooses not to correct them.
I got these comments from the footnotes of *La Bible de Jérusalem,*original edition.
Verbum