Honor is a social norm, so it varies from culture to culture. Because I’m not immersed in the cultures where one must kill one’s own to defend one’s honor, I do not understand the reasoning behind those acts. But let me try.
If a member of my family transgresses against the norm, thus causing me shame, by killing that person, I remove the cause of the shame? Is this a variation on on the concept of out-of-sight, out-of-mind?
It seems to me that would simply trade guilt for shame.