1)
What is the meaning of "Dashti"?
1.
Radak: I will strike [your flesh with thorns].
2.
Radak, based on Targum Yonasan: [I will cast you naked on the thorns, and] trample [on you with my feet].
2)
What are "Barkanim"?
1.
Rashi: They are [another kind of] thorns.
3)
Why did he say that he will afflict them via thorns?
1.
Radak: Sukos was a place of thorns. "Hasmalei v'Sukos Oro" means [that his skin was full of] thorns.