Okay, it doesn't say this is a manga only discussion so I'm gonna have to wrap this one up with spoiler tags.
Observe at your own risk...
Spoiler for Manga Characters:
Alright, so me and a comrade of mine got into a... discussion concerning one of the Eleven Supernova, Trafalgar Law. His power involves the ability to create a contained "room" where he can manipulate and splice body parts with any other objects or persons present in the space.
My friend reads this and starts laughing saying, "If this kid ever fights Robin, he's going to be so screwed." He explains this becuase, for one, Robin can simply duplicated body parts onto any surface so losing an arm or even a head is presumably no big deal to her.
He also came up with one of our more "out there" theories; if Law replaces Robin's arm with say a sword, that sword is now "part" of her body. Therefore, would she be able to start duplicating swords from any surface? I found it to be an interesting concept as Law's ability seemed far too God-modded for my liking at first glance until my friend mentioned this.
So, could Robin act to Law as Luffy did to Eneru, his absolute weakness?
Robin was the only one of the Strawhats who acknowledged his status when they first met, that itself could be a hint at a future confrontation between the two as she has the most intel on him.