Simple. Look at the sword shown. The weapon has a stat called speed. If it was the only sword why would we need to know what the speed of it is. It would just be built into it as a weapon and we would never need to know but it's shown. Therefore we are seeing it to compare with other weapons just like rof and impact. So there must be more than one sword. Another point is the name. Arc Edge. And it states it's not as effective against arc when using it as a shield. This lead any deductive reasoning to believe there should be a void and solar version as well for the same effect.