The process of the creation of a martial art from the diagram of a spell wasn't an easy one.
The first phase consisted of the identification of what effects each line of the diagram produced.
Then, a cultivator had to reproduce those lines with his body to obtain a similar effect.
The issue was that a spell was generated with a mixture of mental energy and "Breath", those two energies could be manipulated easily, it wasn't hard to follow the rhythm of a diagram with those.
A martial art, however, needed for the body to execute that rhythm while following the lines of the diagram, it was impossible for a material figure to have the same maneuverability as something immaterial.
That was why martial arts were generally weaker than spells, the body would not keep up with the rhythm of the diagram and would produce weaker effects.
Also, due to the fact that the Shadow step was a rank 0 spell, its diagram was extremely simple, it wasn't created to produce strong effects.
