Been there. I tossed the spear of night accidentally and when we went to talk to the nightsong we couldn’t kill her and had a very confusing cutscene with Shadowhart. We had to redo the Balthazar fight

You could just leave it equipped once you get it. That’s what I tend to accidentally do.

My condolences.

(…I should put it back in my inventory so this doesn’t happen to me.)