Hello,
This quest has bugged for me. What I did was I got the quest from Tarquin in front of the graveyard, then I proceeded to take both pieces of the sword (the one in the graveyard and the one in bloodmoon isle) without talking in between with him.
So now after I have both pieces and I want to turn in the quest, I only have these 3 options:
https://imgur.com/a/kHUVk
Is there anyway I can fix this, or can you please solve this bug?
I love this game very much and it's very annoying that I can't complete this quest.