Spanish and European armor at the time of the conquest of Mexico was typically constructed of steel and made into plate metal or chainmail (mail).
High quality European armor during this period was capable of effectively protecting the wearer from a variety of melee attacks and projectile impacts, including but not limited to swords, spears, maces, axes, arrows, crossbow bolts, and in the case of thick, very high quality armor, some musket and pistol shots. Plate armor was excellent in terms of its defensive qualities, but it was heavy and often limited mobility. Plate armor was typically worn by wealthier soldiers, and is often associated with Spanish cavalrymen. Brigandine armor was made by fastening small steel plates to a linen garment and provided good protection without sacrificing too much mobility and comfort. Chainmail (or just mail) armor was flexible and protected against swords and other melee weapons, but was heavy and not terribly useful for stopping projectiles and penetrative attacks from spears and other polearms. It was often worn in conjuction with padded linen. Lower status conquistadors and skirmishes (crossbowmen and musketeers) often wore garments of thickly padded linen or cotton. Other footsoldiers opted to wear padded armor for its effectiveness against projectile fire and relative comfort in the warm, moist tropical and rugged, mountainous environments of Mexico, South America, and the American Southeast.
Aztec arms were typically constructed of wood and obsidian, making them practically ineffective against Spanish armor. Obsidian was incredibly sharp, but also very fragile and tended to shatter upon impact with a hard target. The variety of hardwoods utilized by the Aztecs in the construction of their weapons makes it difficult to determine how effective they would have been against Spanish armor, but well made steel armor doubtless stood up to repeated blows, even from heavy wood weapons such as clubs and cudgels. The blunt force trauma of impacts from such weapons was probably painful, disorienting, and potentially lethal, but repeated blows would have been required in order to kill a well armored target.