Katanas are often made proudly to withstand the edge to edge impact.
I must humbly disagree here, Hock.
Katana, like virtually all other Asian swords, are differentially heat-treated--i.e., the edge is super-hard, and the back is soft, to keep the thing from shattering. Parrying with the edge of a
katana will result in very bad chipping of the blade.
With most later European swords, the weapon is given a stiff "spring" temper throughout the blade, so the edge is tougher (but it also needs to be sharpened more frequently because of this). Also, later European swords typically feature a blunt
forte, and this is where parrying is performed anyway, so edge-to-edge parrying is not a big deal. Edge parrying was certainly the norm in Western European cut-and-thrust systems (broadsword, backsword, cavalry saber, naval cutlass, spadroon, & duelling saber).