TK-421
I Do Not Sow
Illifer - hi there.
So that's where it came from. Now I remember. It's an interesting vision - Sansa crying herself to sleep at night and Arya watching silently and secretly (because of something Arya has done to Sansa or someone she cared about? Or is it just hinting at things that have already happened?)
No doubt it's referring to Sandor, Jaime, and Gregor, but I just don't see how it connects back to Sansa (as it's not a giant made of snow but a giant in a castle made of snow). I stand by my original assumption, and I'd say that the "darkness and thick black blood" part are definately hinting at what becomes of Gregor post-Oberyn. I mis-quoted earlier about him being described as a stone statue or giant, but Tyrion thinks that Gregor "looks as though he's been chiselled out of stone". I don't know if that equates with certainty to "in armour made of stone", but it seems plausible.
One thing I feel pretty sure about is that Sansa will not actually be slaying any giants (or Gregor) anytime soon.
This is the dream Bran has in AGOT when he is flying with the crow. I always took Sansa crying herself to sleep was because it was just when Lady was killed and Arya was silent because he did all her crying on the inside. This was Bran seeing things happening as they just happened.