Crystalline Sword - Where does it drop?

I have played thru RP with few characters, and I have never ever seen Crystalline Sword drop.
But I see people selling rares and purples quite often.
The only place I could think of that sword dropping is the same place where eternal shields and ghostly staves drop - The Underworld.
But no, I farm there often with my 55hp monk and still never seen a single drop.

There's been past threads that covered this already. Try using the search and you'll find out what you're asking for.

crystallines dont drop...u get them from chests

UW/FoW chests <<only purples i believe
HoH chest

Thanks I already found it by searching but it was all unconfirmed.