Yes it did decapitate the horses head, but it took 3 swings and each swing he had to saw it, but still it was impressive. Aztecs will more then likely have the sling for long range but the Africans have long bows with has better accuracy and range. The Africans had great weapons and most of them were multi purpose take a look at this knife, great for a close range weapons but look how its designed its the perfect throwing knife.

http://www.eriksedge.com/africasword2.jpg