"It can slice bread as thin as you wish, and doesn't crush crusty bread as you cut."
Even a razor-sharp straight edge presses down before it cuts through bread. Serrated teeth grip the crust and cut instead, so a sourdough keeps its shape and the crumb stays intact. Same principle on ripe tomatoes and layer cakes. AUS-10 Damascus San Mai with an ebony and rosewood handle, on the one knife most kitchens still buy cheap, and a wooden saya so it isn't rattling around a drawer.