Attacking with the edge works best against unarmored peons. When you hold the sword upside down though you get a nice mace to crack open skulls with, right through the helmet too. Half-swording is also handy against them tin cans.

It seems so. Half-swording apparently involves a whole bunch of non-standard anti-knight grips and movements.
It gives you extra leverage and control, helps with blocking and disarming, shifts the balance of mass in the weapon and concentrates the force of blows in a smaller area.