Drawing damaged leather using charcoal I'm currently drawing Wonder Woman with charcoal. While drawing I noticed that the armor has scratches:

Artwork by Shierly Lin. Click for larger version
Since it's a charcoal drawing, I'm having difficulties, because when you use it, you blend it (I think, as it works for me), but the armor has a weird texture like if they drew it with pencils, not charcoal, I don't know if I'm being clear, I don't know how to draw that texture.
I'm using 2-6B charcoal pencils and hard, medium, and soft charcoal sticks and graphite to make it smoother.
How can I properly draw those details (scratches on the armor)?
Damage to the leather is just like any other detail. It is created by relief (changes in height) in the surface, so it is rendered the same. Just like the embossed areas of the leather, one side of the impression will capture light and the other will cast shadow.
So to draw scratches etc., you would use light edges and dark edges along the contour of the scratch.
As far as specifically using charcoal versus pencil that is a stylistic choice. If the charcoal medium does not deliver the look you want, then you would probably want to stick with pencil.