You can have it sharp with shaped charges array sitting a bit deeper and sideways, and new edge breaking out as side effect of shaped charges exploding, rinse

You can have it sharp with shaped charges array sitting a bit deeper and sideways, and new edge breaking out as side effect of shaped charges exploding, rinse and repeat, about 5 times for a regularly sized sword. Even more interesting alternative is to have some quick blade switching machinery to switch on-the-fly between the actual blade edge and the shaped charge array and to add some feeding machinery of shaped charges into the array (and to have some stretch-shaped charges instead of the rounded ones)