John K Jordan
I always ease the sharp corners. I agree a belt sander would work but it can be done with stones too, or better, diamond hones - anything to knock off and smooth the sharp corners. The worse thing about nicks in the tool rest is they can catch the skew and prevent smooth sliding. FWIW, the tool rests like the Robust with a hardened steel rod on the top should not develop nicks even with the skew corners sharp. I like them eased anyway since it makes the tool more comfortable for some grips.
Mike Darlow, in his book Fundamentals of Woodturning, suggests rounding the sharp corners to the radius of a pencil lead is sufficient. He does recommend to grind to a semicircle, hone and polish the steel. He writes that a linisher (belt sander) is better for this than a grinding wheel.
Thompson skews and some others are made with a smooth semicircle instead of a flat on that edge. This is nice for several reasons. However, be advised that expert Richard Raffan suggests after sharpening such a skew to grind a flat below the edge to make a two sharp edges to meet at the short point. (He writes about this in his book Turning Wood.) This can help with some cuts such as cutting beads with the short point. I don't do this on my Thompson skews. Mike Darlow does not mention this in his books.