Mourning's Ends Part III (project led by Chris L) is a currently unsubtitled quest to be released in 2013 or 2014. It is to be the ninth quest in the Elf Quest Series, and it was confirmed at RuneFest 2011. However in the 4th live Q&A session with Mod Mark, it was mentioned that it would be more likely that Mourning Ends Part III would be introduced into the game in 2014 instead, due to the huge amount of content that needs to be developed for it. There is a possiblity that you will obtain a crystal halberd during this quest or as a reward.
Little is known about the quest, but it is known access to the Crystal City of Prifddinas will be granted as a reward, and it will be released alongside the Elven Task Diary.