As this is a specialist subject, it would be unfamiliar to us.
However, let us take a look to understand the blades better!
High carbon steel, alloy steel
These are important raw materials for crafting blades. The terms denotes steel that has had elements added to it for extra stability & functionality.
Steel + one of five* elements = high carbon steel
Steel + elements outside of these five** = alloy / special steel
* carbon, silicon, manganese, phosphorous, sulfur
** chrome, molybdenum, tungsten, vanadium
Simple! These are the special properties of the raw steel used by Nomiya Blade. These properties may be understood slightly differently depending on the specific craftsman
Blue steel (HRC: 60 – 64)
The highest grade steel. Its extremely high degree of hardness allows it to retain its sharpness. Without appropriate care though, it can easily rust.
Stainless steel (HRC: 57 – 60)
The most widespread steel alloy. Its greatest quality is its low propensity for rusting.
VG-10 (HRC: 57 – 61)
A very popular high grade stainless steel. Possesses both hardness and resilience.
SWD Steel (HRC: 63 – 65)
High purity high carbon steel. Sharp and easily honed.
AUS-10 (HRC: 60 – 61)
High grade stainless steel. Its high degree of hardness allows it to retain a razor sharp edge.
Together with the development of steel, blacksmiths developed a range of new raw materials through a process of trial and error, and pushed forward the technology and nature of sword smithing.
These blacksmiths were frequently able to conjure innovation in their workshops that cannot be explained even with modern technology. You could assume them to be magicians rather than blacksmiths!