Ok, it's kinda difficult for me to see exacyou if that is nasty nasty rust or alot of discoloration in a couple spots.
So first what I'd do is unpin the blade, then single edge razor to scrape the blade and get any scaling off.
Take some metal polish and polish the blade, for me this gives me a better idea of what I will end up doing.
If there is pitting, you will need low grit paper. I recommend since this is your first start around 400 wet/dry and take your time. Use something other than your finger on the tang so you keep nice clean edges.