ian't this one of those devices where we aren't clear on how it was actually used? I mean we know of ways to use it, but not what it was historically used for
It's generally believed to be either a torture device, a sex toy, or both. Given it's Koakuma, who's into the really dangerous stuff (compared to Ran, who will shag you to death but is otherwise very vanilla), she's probably intending to use it on a guy for both purposes.
Pretty sure that's a used to help remove corks from bottles.
If only. Sadly for many drunkards, until the goddamn 1800's corks either had an excess at the top to pull on, or one had to break the bottle to drink from it--there are even special knives for it.
Nope, that's for wrecking an orifice; either slowly breaking a jaw (and all of one's teeth too) or the much less terrible fate of tearing open an anus.