Although Ves felt he had made a disappointing first D-arm, the experience had taught him a lot of lessons.
He felt confident he would be able to do a much better job next time.
Ves and Ketis did not immediately throw away the D-arm. They still wanted to gather more data, so they methodically tested out its hardness, its cutting power and any other weird stuff it might have.
The Workshop of Creation offered plenty of testing facilities that allowed them to thoroughly understand the properties of the weapon. They gained more precise numbers than the ones collected by Ketis' handheld multiscanner and also managed to record the properties that it couldn't gather.
All in all, despite the fact that Ves apparently wasted most of the power of the 'demon' locked inside Lucky's gem, the pink and awfully spiky knife was still a qualified D-arms.