Just for information, I once reveived a blade that was discoloured due to heating. (maybe it was done too fast / too hot).
Without any knowledge of metals at all, I decided to reheat it gently and while cooling down, I rubbed the surface with aluminium-foil. (just the simple foil you use in the kitchen.) This made the discolouring disappear.
There will be better and more metalurgic ways to solve this but just a tip.
And best wishes to all. May 2007 be a prosperous and above all healthy year.
Best regards,
Willem