West Wind blew there;
A wind from the west would come from Valinor, land of the Valar (gods), other assorted divine beings, and those elves who do not reside on Middle Earth proper (including many from the First and Second Ages).
This can symbolically be understood as Aragorn claiming Gondor had the favour of the gods. Given their assistance to the line of Elendil by sending the Istari (five wizards), and friendship with elves, the implications were plain.
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