The antonyms for the phrase "more keen-edged" include dull, blunt, flat, obtuse, and rounded. These words describe the opposite of something that is sharp and precise in its edges. A dull object lacks sharpness and is incapable of cutting or slicing through anything, while something blunt has had its sharpness worn down or dulled. Flat objects have a smooth, level surface without any sharp edges, and obtuse objects have an angle greater than 90 degrees, making them dull by design. Finally, rounded objects lack any sharp or defined edges at all, making them smooth and soft to the touch.