It should not be blurry. It’s simply a hand painted texture at 512×512 resolution. Might be the filter method of your software or the engine you are using? Perhaps the mip-mapping setting or maybe you are zooming in too close? (in which case any texture will eventually be blurry)

That is something that keeps sneaking into my folders every time I open the files in Maya. They are of no use, you can delete them. Sorry for the mess!