Tragic...
The original factory finished powder coated epoxy psint never was particularly hard wearing to begin with.
No paint ever is, i guess.
Fair warning though;
anything done or applied
to the knife
would further depreciate its collector value.
But its yours and i understand how a marred look can really be upsetting

so, You could have it done professionally at an auto paint shop.
Or you could DIY with a spray can
of wrinkle paint.
It would be better to remove all
the old paint for an even surface.
Be sure to mask up areas that
you dont intend to spray over.
And lay off any applied heat
to plastic parts and rubber !
If you haven't any experience
do a test run on a metal can before
attempting it for real on your knife.
Best of luck!