Whether it’s the heat treat, the steel, or the edge geometry, I don’t know, but my Spyderco Gayle Bradley GB1 holds an edge better than any knife I one. Not just by a little bit, but by a noticeable amount. So maybe I should quality and say I want a M4 Sebenza heat-treated by Spyderco. Regardless.....I can’t tell much difference between S30 or S35VN, but M4 is a whole different level. The downside for some is it is not stainless and blemished readily. I actually like this as well, as I like the truly well-used, truly worn, and well-loved esthetic. The blade developing character adds to that for me.