Martial Techniques: There are five grades in total - A, B, C, D, and E.
Each sect or clan has at least given martial techniques in total, one from each grade. But some strong sects may have more.
To be precise, grade E martial technique is comparable to the strength of an Lv.10 cultivator.
Grade E: Lv.10
Grade D: Lv.20
Grade C: Lv.30
Grade B: Lv.40
Grade A: Lv.50
More or less this is correct, but there are some martial techniques, that cannot be compared by strength alone. For example, martial techniques of a poison clan or a clan dealing with illusions or mist mostly have defensive or illusion or poison type techniques which can harm or defend attacks from even a stronger opponent!
In any case, to be able to learn the martial techniques, there are three requirements:
1] One must not be above the Lv.30.
2] One must not have any beast souls.
3] One must train their mental strength daily.