شَخْصًا شَحِثَ الْخِلْقَةِ
A person thin and frail in physical build.
Shakhṣan is the person whom the narrator sees; shaḥitha al-khilqah describes his outward physical form. The phrase does not establish any lack of learning or moral worth.
The story first gives us a weak-looking body before describing the power of the man’s speech.