Answer: The tool being described here is a razor.
Explanation:
Razors are used to cut hair at an angle, which helps to create a softer, more textured look by thinning the ends and creating a diffused line. The mention of the tool having only one blade aligns with typical hair razors used for cutting. Razors are generally not recommended for use on curly, coarse, wiry, or overprocessed hair as they can cause damage and split ends in these hair types.
