I think in 15n20 it is far more likely that the Nickel content is reacting with sulfur compounds than the 60 ppm or so of sulfur is being released from the steel.
All carbon steel knives smell. May be more, may be less, but they smell.
I stopped fighting it. Very few people feel the smell in the food, if none.
Lucretia, have you been sick lately? taking antihistamines or had a runny nose or dry nose. All of these things can make your receptors overly sensitive once you get better. Plus the whole super woman sense of smell thing.
I haven't lived the life I wanted, just the lives I needed too at the time.
I'd be interested to know how the reaction happens, both with sulfur and whatever is in the onion, and the sulfur in the onion with the nickel in the steel. Some knives give off a funny, metallic smell(my shig, my parent's sabs), and others give off a stench(my cck).
The number of competent chemists contributing to this thread is overwhelming.
Have you tried Summers Eve for Damascus - when your knife has that 'not so fresh feeling'?