SC - French knife

[Seton1355 at aol.com]

I helped set up a Hadassah rummage sale this evening.  I was lucky enough to 
get a bunch of leather & suede.  (Don't know what I will do with it yet)  And 
 (and here's the food content)  a French 12" chef's knife.  full tang.  The 
knife is about 40-50 yrs old.  It is still sharp!!  But, the sides of the 
knife are sort of yucky.  Not rusty just yucky-spotty looking.  How do I 
clean up the knife?
Thanks in advace.
Phillipa