The bright side is that the right leather repair kit can effectively address typical issues, including discoloration, punctures, cuts, rips, scuffs, cracks, abrasions, or damage resulting from bites.
While serious leatherworkers build their own kits from scratch, a pre-assembled leather repair kit is a convenient way to start out with fixing up and refinishing wares you already own.
For leather filler, it suggests Arcssai leather and vinyl repair kits ($19.90 on Amazon). For a good color match, you may need to go over the area multiple times with a marker, shoe polish or paint.