1)
What is "Kotz Munad"?
1.
Rashi: It is a thorn that is initially soft, but in the end it hardens. 1
2.
Radak: It is a thorn that one who finds it discards it.
3.
Malbim: It only harms one who touches it, therefore everyone is Nad [goes away] from it.
1
Targum Yonasan: Resha'im are like thorns that are initially soft. If one has mercy on them and leaves them, they harden, and one cannot touch them.
2)
Why is it not taken by hand?