itztli (Mdz30r)
This element for an obsidian blade (itztli) has been carved from the compound sign for the place name, Tzinhuitzquilocan. It is an upright leaf shape, an oval pointed at both ends, much like a flint knife (tecpatl). It is black with four white teeth running vertically up the left side. The teeth are surrounded by a curving red line that suggests gums.
Offerings from graves found in the Templo Mayor (see below) show how these types of blades could be decorated with faces.
Stephanie Wood
c. 1541, but by 1553 at the latest
Photo, by Robert Haskett, of Offering 125, taken 2/25/2023.

itz(tli), a sharp-bladed instrument of obsidian, https://nahuatl.wired-humanities.org/content/itztli
obsidian knife
Codex Mendoza, folio 30 recto, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 70 of 188.
The Bodleian Libraries, University of Oxford, hold the original manuscript, the MS. Arch. Selden. A. 1. This image is published here under the UK Creative Commons, “Attribution-NonCommercial-ShareAlike 3.0 License” (CC-BY-NC-SA 3.0).