Several people said that you can pickpocket Celestial Fire off Trias before you fight him. I don't want to kill him (I'm lawful good) and I don't have Vhailor with me to do the job for me either. When I try pickpocketing him all I get is the clestial thing scroll and a blood charm.

I have around 85% PP on her.

Are you playing with any fan-made content, or you just installed the game?
Maybe it was something Qwinn changed.
I suggest using a editor, like this, to add Celestial Fire to your inventory. Of course, make a backup of your save files first.

Well, I've taken that in consideration, but in Qwinn's changelog I couldn't find anything relating to CF being pickpocketable or not.

I don't know if it's true, but in this page, it's written:
Even if TNO cannot approach Trias in the second meeting, Annah can. Qwinn's Fixpack announced plans to modify the game to make it impossible to steal from Trias in the second meeting, sometime after 2009.

Indeed you are right.. but such thing was not mentioned in my changelog, thanks for the info, that must be it - even though I CAN steal from him, I can't get the sword..