I used to use a butter knife or a dinner fork to tease out roots growing in tiny crevices or in between bricks or pavers. But I recently got a hori hori knife that changed my whole way of looking at the world (of weeds). Here's why:
Above: I have a Carbon Steel Hori Hori; $23.90 from Hida Tool. It's turned out to be an all-purpose hand tool—a digger, a grubber, a trowel, and even a winch. You can jam the blade under a heavy rock and use leverage to lift it up long enough to pull weeds out by their roots.
Above: The serrated blade is sharp enough to hack through a clump of bedraggled irises or lilies; the cleanup work goes faster if you don't have to go hunting for the pruners.
For more Japanese garden tools, see "Tools of the Trade."