The warrior's physique was basically a skill or ability that could be developed by honing and training the body with mana. With this physique, the body could heal injuries and cuts on its own, as long as mana's available.
Since Elementalists couldn't use raw mana, and only used a refined form called elemental mana, gaining warrior's physique was borderline impossible for them.
Coupled with the fact that they relied mainly on their spells and elemental skills, it was even harder to develop the physique.
There were only few from the sixth mana core stage and above, who were known to have awakened the ability by properly training their physical bodies and honing their elemental mana.
