AFAIK 'Signature' weapons have only been added through limited time promotional events (Lightning returns) which later became purchasable through the Mogstation. It's highly unlikely they'd release Brotherhood through veteran rewards, as they'd also have to create weapons modeled around FFX for the other jobs to release simultaneously. Going with glamour armor based on past seems much easier.
Unless they release a FFX-3, or other title in that Universe, I can't see them going ahead with this.