The prop used by infantry and female citizens to slaughter domestic animals looks like this:
As you can see it's a dagger designed for stabbing people. Cavalry is even worse: they use full-size swords.
This is how a sacrificial knife (μάχαιρα) looked like in reality, at least in the Greek world:
It would be great if someone could model them to replace the currently used prop.
For comparison, the falcata.xml uses 5 variant meshes, gladus.xml 6, xiphos.xml 5, and kush_nubian_mace.xml 15, and I daresay their shapes are more similar than the 5 knives in @MrLux's screenshot. Besides, those other weapons are used by only a few actors, whereas the knife is used by the slaughter attack animation of all infantry and female citizens.
I don't know how much it affects performance, though I wonder whether it's significant in this case.