This was at the recommendation of Mahmoud Abbas, as a followup to his similar requests to form a UN investigation in 2012. Abbas called for the UN to investigate last month as well and the internal PA investigation committee already employs 100 people who are apparently being paid by Western funds to push papers around in giant circles.
Saeb Erekat, member of the Executive Committee of the PLO, said "At the request of President Abbas, the Council of Arab foreign ministers decided to assign permanent representatives of the Arab countries in the United Nations to work for the formation of an international investigation committee the martyrdom of President Yasser Arafat." Given all the time and effort that numerous "investigations" have expended so far without any findings, Erekat might as well have said, "We will not stop forming commissions, committees and inquiries until we can definitively blame Arafat's death on Israel."
Keep in mind that Abbas' government has been on record as blaming Israel for Arafat's death since at least 2006.