Bigger question Is why is Trump even talking about belt buckles and knives?
When you take a step back, you can see Trump's strategy more clearly.
He knows he is not only running against his fellow candidates but also against the media. So he gives the media just enough information that they cannot help but smear him. By now, the voters can see what the media is doing (Trump has pushed the meme for a long time that we need to be on the look out for such) and when the media smears Trump, the voters hold it not against Trump but against the media...and Trump wins another round.
Secondly, Trump's strategy against his fellow candidates is to hang "anchors" around their necks so that when voters think of them, the anchor comes to mind.
Jeb = "low energy"Marco = "sweaty little kid"
What he is doing with Carson is using Carson's own book to anchor him with "pathological (hidden) anger" and/or "liar."
“What he is doing with Carson is using Carson’s own book to anchor him with “pathological (hidden) anger” and/or “liar.””
But that is dishonest.