"-less" means "less than"? Or "lacking"?

[Dennigan, Darcie]

I recently bought "stainless steel" forks and knives from Crate and Barrel.
The product description (included inside the box, not posted outside) read
"Will It Stain?
Yes. The name says it all. It's stain-less steel, not stain-free steel! Nevertheless, it will stain much less than other steels: silver, bronze, etc. With proper care, staining can be minimized or eliminated."
 
Is this anything more than the manufacturer's careful wit? I wondered if that history is correct-- did the suffix "less" at one point simply indicate a comparison, as in "less than" or "comparatively little"?  I had always thought it meant "without"-- painless = no pain, wireless = no wire, etc.  
 
Thanks, 
Darcie Dennigan