Repair scuffed leather

Depending on the type of leather and depth of the scratch, you can often rub the scratch gently between your fingers (one on the outside and one on the inside of the bag). The natural oils from your fingers act as conditioners and can fix the bag quite well. I have a few bags where the designer specifically recommends this method (Vin Baker, for example).

If you're not sure, definitely go to a shoemaker--they have the most expertise.