itztli (Mdz48r)
This element of an obsidian blade (itztli) has been carved from the compound sign for the place name, Itzteyocan (see below). It has a somewhat unusual block of obsidian that is topped with a piece that is much thinner and curves to the right.
c. 1541, but by 1553 at the latest
A photo by Simon Burchell (marked as Creative Commons) shows unworked obsidian blocks with thin, sharp, curving blades behind them.

itz(tli), a sharp-bladed instrument of obsidian, https://nahuatl.wired-humanities.org/content/itztli
obsidian blade
Codex Mendoza, folio 48 recto, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 106 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).