Yes in cold days, that harpoon he makes of ice and soulfire in the barfight with the outsider, he who walks before
Nope, that was fire. It made, "an arctic-gale hown and a spiraling harpoon of blue-white fire burning hotter than anything this side of a star" Which is not what usually happens with soulfire infused fire... And considering some of the adjectives it is understandable some might think of ice.
The winter knight side of him did rear up moments later though, "as my fist sailed forward, there was a sudden thrill that flowed up my arm from my hand, something delicious and startling. I had barely processed that when I heard a crackling noise, and then saw glacial blue and green ice abruptly coating my fist..."
I don't think we've seen soulfire plus winter knight ice yet. I am really looking forward to the fight with outsiders with Eb in the new book, because I think we are going to see if Harry overshadows Eb in the fight against the outsiders because of his ability to withstand their mental attacks (starborn), the added effect soul fire has, and the apparent instinctive support he gets from winter against outsiders. Literally every power up he has gotten is even more effective against outsiders than against anything else. I think Eb is going to be shocked after he sees Harry fight an outsider.
If so, I suspect Eb will be like, "Oh my God, you do realize X, right? We need to talk later." Only for Eb to die later so that Harry has a little more to go on, but not all of it. Plus, seeing Harry as the guy powered all to heck to fight outsiders is what tips the balance and causes Eb to leave Harry the blackstaff, which then powers him up even further since it syncs with the winter knight mantle sooooo nicely.
Plus, since the staff stays with him somehow (seeing as how it could just appear in Eb's hand previously) it makes a nice plot device for when he does mirror mirror as a power-up he can use against his alter-self even after he's summoned right out of his shower or something...
