Bisht: It is a traditional men's cloak. They are usually worn on special occasions, like weddings and religious festivals. There is a further meaning to the bisht. They are usually worn by secular officials or clergy.
A bisht is usually worn for prestige on special occasions such as weddings, or festivals such as Eid, or for Ṣalāt al-Jumuʿah or Salat al-Janazah. It is usually worn by secular officials or clergy, including tribal chiefs, kings, and imams, over a thawb, kanzu or tunic.
I think they meant for it to be a big honour, because you see the Sheikhs/Emirs wear it on royal visits and special occasions. So I think it's them trying to crown the winning captain that way.
Nobody will remember it though, I don't personally care its the first Arab world cup and Messi ends his international career with a WC and a Copa America.
I do think they should have given Messi the option though