The Giros knife cuts through tough roots with ease. This seems a whole lot slicker than punching through plants with the blunt end of the spade or trying to pry them into pieces with your fingers. I also used the knife to to divide a huge clump of asters. In that case, I didn't dig up the whole plant. Instead, I just cut off a quarter of the plant and then dug that part up. It came out easily because the roots were separated from the rest of the plant.
And then there were two!