I recently received a Dogfather Le. I have used it a few times to 'deThatNeighboorify' my yard.

1) What is the best way to remove stains from satin SR77? I do not believe it is rust but the discoloration does not seem to come off with sand paper.

2) Should I be overly worried about the blade corroding in the humidity of Houston? It has been indoors since I purchased it but it seems to have more discoloration on it then when it arrived. I have used the knife several hours outside so I guess it might be just be wear.

3) While clearing some weed stalks and chopping some small trees I stuck a cinder block and a rock. While cleaning up I noticed several sharp dents in the edge. I was unable to straighten them with a steel and needed ~20min with diamond stones to get them out. I do not believe I put that much force into the swings and was surprised to see the damage. Should I realistically expect the edge to not have been damaged in this situation or is it possible that the edge I received it with was too thin?