Jumping into the symbol vs. mascot thing..
As it stands..the "shield and swords" is the symbol of AG. There is no promotional effort put behind it to dictate it the mascot.
The mascot and symbol can be one and the same (Such as the St. Louis Cardinals, with their symbol being the cardinal on a bat, and their mascot being Fredbird the Cardinal) that does not have to be the case (such as the Colorado Rockies, with their symbol being the mountains, and their mascot being Dinger the Triceratops)
The problem, however, with the "shield and swords" alone is that it has limited exploitable abilities. For irl usage..it is unnatural to carry your swords sheathed in the shield..and having it on ones back would only be too close of a resemblance to Link in LoZ. Then for game usage, unless it is given the ability to move on its own and possibly talk, it would require something else to hold it, thus giving the association to the entire image and not just the "sword and shield"