The fighter was actually an "Ugly" design, having been assembled from parts of both the TIE fighter and the X-wing. Unlike typical Uglies, which were haphazardly cobbled together from whatever parts were available, the Chir'daki was built according to a specific design and apparently had no more variation from one fighter to the next than would a factory-built craft.
The S-foils of the X-wing fighter were attached to a gyroscopic mount which was then mounted onto the main pod of a TIE fighter, similar to the design of the B-wing starfighter. The Death Seed used the twin ion engines of the TIE for propulsion, and relied on the X-wing engines to power the lasers, hyperdrive and shields. The resulting craft had a bit better maneuverability than the standard TIE, but was a little slower. The Chir'daki starfighters were also related to TIEs in the fact that they also had no life support systems, hence their pilots had to wear pressurized flight suits like Imperial pilots did.
The S-foils gave the Death Seed all the laser power of an X-wing, giving it more firepower than a TIE/LN. The Twi'leks decided not to incorporate any concussion missile or proton torpedo launchers into the design, as those weapons were very difficult to acquire.