On Wed, 15 Apr 2015 16:25:55 GMT
(Scott Lurndal) wrote:

If a handsaw blade hasn't rusted, it's been treated well.

or made in low O2 environment or lots of other possibilities since
steel making is complicated and the issue is more complicated when
you throw in something made long ago where the technique was only
know by few people including the alloy's composition
i.e. did they add special ingredients