Given the warlike tendencies of the Aztec culture, it seems safe to assume that they would incorporate the use of bronze and/or iron weapons in their culture.
Large deposits of copper and iron are present in South America, though not primarily in regions controlled by the Aztecs. However, mesoAmerican metallurgy did include copper and copper/tin weapons. So the question becomes why did the Aztecs not use this resource. Digs in the areas controlled by the pre-cursors to the Aztecs do find bronze items. But this is not limited to the Aztec pre-cursors, they also find Aztec tools and weapons made of bronze.
So, was this a cultural question or an economic question that prevented use of bronze weapons on a large scale? Given the relatively small quantities of bronze in Aztec and other mesoAmerican cultures, I would have to assume that bronze was not sufficiently cheap for widespread use. However, I would also suggest that if it were sufficiently prized for tools and weapons, it would have been produced and used in greater quantity.
From a practical matter, gunpowder weapons of the Spanish and the fact that Aztecs were brutal rulers that inspired the Confederacy of Tlaxcala to join the Spanish against the Aztecs were much more critical factors. Spanish numbers were always very small and had the Aztecs had good organization and military leaders they could have easily defeated the Spanish without bronze or iron.
Widespread use of bronze/iron weapons again the Tlaxcala would also be very likely to have made a difference in battle. The Aztec did not really make effective use of their archers either.
The biggest problems are training, organization, fighting style, etc. not the availability of better weapons.
Given that the Aztecs actually had bronze weapons, I don't see how the discovery of bronze or even iron weapons would be itself make a large difference on the battlefield.
Note: the Aztec culture did not exist in 1000 AD, but they are descended from a culture that did have bronze weapons in 1000 AD.
I want to add that copper and bronze weapons were very rare among the Aztec. For sharp edges they generally used flaked obsidian which is extremely sharp and they had weapons that used obsidian very effectively. The price of bronze was very high. Still they had the technology, just did not use it primarily.
Note also that the Spanish made bronze cannons from locally sourced copper and tin to attack the Aztec. So the resources were available had the Aztec sufficiently valued the bronze for weapon use.
A big part of the problem with the Aztec war technique against the Spanish was that they went to war in order to capture subjects for human sacrifice, not to simply defeat the enemy. While this was historically effective against their neighbors, it was poor strategy against the Spanish.