First, tungsten is not light. It is one of the most dense materials on Earth. It has over 1.5 times the density of lead. Tungsten carbide is somewhat lighter simply because it has lightweight carbon in it. If you are taliking about a tungsten alloy, you probably mean a steel with sime tungsten in it. I know of no tungsten based alloys since the primary desireable property of tungsten is the high melting point and any alloying will lower the melting point. As far as alloy steels go, they are softer than tungsten carbide (will scratch more easily) but they are much tougher (will not fracture under impact) and are lighter.