Here is a closer look at the tsuka wrappings the the negative-space diamonds. Inside the diamonds, we see organic, seed-like shapes that provide a bit of texture. Underneath the wrappings, there appears to be a an amulet of connected geometric circles.
The tsuba is pre-Edo, with functionality being its main objective. The negative space is not part of the design, rather it is simply a series of holes for the blade and knives.
The metal plates are, however, entirely decorative, and their designs are plated in gold.