a sharp-bladed instrument of obsidian; also, Itztli ("Obsidian Blade") was a deity that was part of the Tezcatlipoca Complex of deities that relate to power, omnipotence, often malevolence, feasting and revelry.
itzcopeuhquen in itequiuh centomin = The obsidian-blade makers' tax is 1 tomín (Coyoacan, mid-sixteenth century)
cenca vel quiximati in tecpatl, in itztli = they are very well acquainted with flint and obsidian (Tlatelolco 1540–80)
itznepaniuhqui tilemahtli = "The cape with the crossed obsidian knives design"; Seler translated it as "the cape with crossed obsidian points (or obsidian points at the intersections)"
Obsidian knives (ytztli) are given as some of the essential items found in the "devil's houses" (Sahagún).
intla omjc piltontli, itztli qujcalaquja in ijtic cioatzintli in ticitl = if the baby had died, the midwife inserted an obsidian knife within the woman (central Mexico, sixteenth century)
"Itztli, the obsidian knife, was one form of the terrible goddess Itzpapalotl, Obsidian Knife Butterfly, and several of the Aztec goddesses wore knives as skirts or carried them on their backs like babies. Sacrificial knives are often shown with faces, or even as animated gods chasing and devouring victims."
"...a stone knife, and in this manifestation he was known as Itztli, the knife-god. He is thus brought into intimate relation with the hunting deities, of whom this weapon was a symbol."