The Aztec calendar is the calendar system that was used by the Aztec people, a pagan culture that engaged in human sacrifice to the god whose image is at the center of this calendar - Tonatiuh.
Worshipped as the Lord of Heaven, Tonatiuh is usually featured with blond hair due to the golden rays of the sun. The face is wrinkled to depict age and maturity. The tongue always protrudes and is in the shape of an obsidian knife which indicates that this deity demands to be fed with blood and human hearts.
Estimates range as high as 20,000 people per year were sacrificed to Tonatiuh and other Aztec gods. Slaves and captives were the most frequent sacrifices, but women and children were also sacrificed on occasion. The usual means of sacrifice was by fire, drowning, or cutting out the heart.
It is certainly an occult image and represents not just a calendar method, but the bloodthirsty god for whom it was designed.
The questions you raise about these bracelets are completely understandable and I can't help but wonder why anyone would consider such an image to be an adornment.