These selection handles temporarily go away when you resize or rotate an object, which is a good thing. That should probably also happen with the feather slider (and profile sliders) while using the selector tool.
The bigger blue handles make it more difficult to see how the feathered object blends with the rest of the design while you are working with the feather sliders.
If you switch to the transparency tool, the object stays selected but the selection handles seem to go away. But now if you use the feather sliders its easier to see what is actually going on.