Following on from the lazy quick fix above which will leave you with black hands
I purchased some leather acrylic paint from Angelus after watching numerous YouTube videos of how people use it to repair trainers and handbags.
Cost about a fiver each and £2.50 p&p.
They recommend a deglazer first, but it's just acetone which is basically nail polish remover!
My Zeds side bolster has started to show wear after 13 years of being my daily despite climbing