Hi Will,
It's easy to shave down the tape edge ridges using many light strokes with a sharp scraper. Hardware stores sell nice ones with replaceable carbide blades that last well. Ordinary flexible steel cabinet scrapers work fine too, and can be flexed into a convex (or concave, I suppose) scraping profile that is nice for shaving down small areas. I have also used the replaceable blades for ordinary utility knives for scraping epoxy. For smoothing concave fillets, I have read that filing sharp corners on a round washer is also effective. It apparently is either held in the fingers, or gripped with a Vise-grips, but I've yet to try that.
I like to scrape epoxy rather than sand it, whenever I can. It seems to go faster, and creates zero dust. I do a light sanding after scraping, and then apply the microballoon fairing mixture, as Alan Stewart has described.
Anders