I would unpin it for sure. It makes the job easier and thorough. A flush cutting pliers with tape around the pin area will remove them without damage to the scales. I don't have the patience to hand sand my blades, so I use buffing compound on 8" buffing wheels. Depending on the amount and depth of the rust or corrosion, you can start with an aggressive gray (cutting) compound, then go to white, then green (cut/polish). To just polish you can use red rouge at the end and then hand polish with Flitz or whatever. I use green buffing compound and light pressure on the scales. They will cut a lot faster than you expect, so easy does it. Those scales should shine up real nice.