hmmm... maybe I missed something... but I didn't get that.
I still keep thinking Strength: how much force it takes to bend the steel. toughness: how much deformation before the steel breaks.
maybe it's overly simplistic... but I think for the most part it's accurate... and I don't want to over think it too much... (even though we kind of already have started)
EDIT: this was reffering to bld's post.
also knotslip, yes, very true. that's why a knife CAN be TOO tough... If it has some strength too, then it will spring back after deformation better won't it?