Most garden trowels are worthless. They can dig a hole into a bag of potting soil, but that is about it.
Have you ever tried to dig into the actual earth with a trowel? I have. And it is about as discouraging as trying to water your garden with a hose full of kinks.
I have a trowel that works. It is the Wilcox All-Pro No. 100. This 10" fine-pointed trowel can cut through roots and soil. And the sharp edges can slice through a nursery pot if you have a root-bound plant. It is great for breaking up a root ball, opening a bag of potting soil or quickly cutting twine.
This tool is so sharp that when you purchase one ,the beveled sides of the stainless-steel trowel are covered with a piece of plastic so you won't hurt yourself. Love, love, love.
Hyam's Garden Center on James Island has this trowel for sale for only $12.95 each.