Nib file

It will be dull after shaving but you're wetsanding and buffing anyway. If it's a big run don't try to wetsand it out alone. You'll end up removing material you don't want to.

You can also wrap tape around the ends of the blade just leaving a section in the middle exposed. That will protect from accidently digging in with the corners. Works great.

BTW, this is for clearcoat or a solid, not single stage metallic, right?