Thanks for your reply. I'm getting familiar with the technique, and the video was a helpful way to remove the "fringe" when frequency filtering.
However, what I am looking for is more depth into how PS determines "frequency". I suspect it uses some form of edge detection, but would be curious to know if there was actually a frequency being referred to. Lightwaves do have frequency, but separating that way would be more of a warm/cold filter than a sharpness/blur filter.