re: Second urn -working on the top

I typically use a skewed block plane to clean up endgrain like that to avoid softening the edges.  My second choice would be a long-ish hard sanding block like Splint suggested.  You want to do everything you can to keep it flat on that bevel to avoid ruining the crisp edges.  If the burning went very deep at all and you have to do much sanding, you'll probably need to sand all 4 bevels to keep it symmetric to the eye.

The Urn is shaping up nicely!