I fear making BoW undamaging will just make it useless, who will care about a spell that just cools the atmosphere and adds a little fatigue here or there ?
Maybe it could have been done less damaging, or higher level (as Soul Vortex is), or the AI changed to avoid freezing own troops to death, but nerfing it this way doesn't seem good.
BTW in the preview Dom3 version I have (2.79 sent to press) BoW just doesn't work, it's never cast even when scripted
