itztli (Mdz27r)
This element for the noun itztli (obsidian blade) has been carved from the compound sign for the place name, Itzmiquilpan (see below). This blade looks just like a tecpatl (flint knife) in its red and white version, divided by a diagonal line. The tip is red, which may symbolize blood.
Stephanie Wood
c. 1541, but by 1553 at the latest

itztli, a sharp bladed instrument of obsidian, https://nahuatl.wired-humanities.org/content/itztli
obsidian blade
Codex Mendoza, folio 27 recto, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 64 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).