6. Dust release
Disintegrate anything into molecular level
Was mentioned as strongest material that can pierce through anything, also stronger than enma adamantine
4. nine tails chakra
Kusanagi cant break through it, even only in 4 tails form. Amaterasu was also mentioned can burn anything therefor sasuke amaterasu cant burn Naruto 9 tails cloak. So this material was exception from “anything”.
3. Truth-seeking orbs
Stronger than 9 tails cloak. Can perform strongest seal barrier that indestructible by 10 tails biju dama.
Yeah. Really bothered me we didn't get to see Hell Stab: Black! We never even got to find out why black lightning is better. It was just mentioned that it was awesome in a couple of places and that was it.
Besides, I don't thing that the Third's skin is that durable on its own, rather, it becomes almost impenetrable when it's augumented with lighning chakra mode. I'm not saying it's a completely normal human skin without lightning armour, but it's unlikely that the skin alone can withstand such techniques as Rasenshuriken with little to no damage.
Well, but the body alone was given credits as very durable (at least, by human standarts), not just his lightning armour. Otherwise, only the armour of his would be known as "the strongest shield" and not the body as a whole, though combined with the armour as well. Also, it was Raikage whose flesh was compared to the steel and blood - to the iron (however, I admit that could be an exaggeration more or less).