The problem you're having is due to the fact that Freehand converts these effects (including transparency) to bitmap. To make the edges sharper, go to FILE > DOCUMENT SETTINGS > RASTER EFFECTS SETTINGS and set the dpi higher. The higher the dpi, the sharper your edges become (but the more memory it takes, and the slower the program runs). If you are going to be printing at 300 dpi, there's probably no point setting the raster effects any higher than that...
Hope this helps.
-Lyle Schulz-