The artifact/trumpet quest is not essential to the story. The first time I played I missed the timing of it and didn't even realise I had missed something. The story is waiting for the next timed event.Suggestion:
Grab the trumphet. You can then give it to the elf king if you really want to, although there is the third option. Some people will give you an extra option when you are talking to them. If you have already gotten the rescue Loren Steele quest from queen Catherine the elf king will have something to say about that as well.
