Once again, your big images looks great, yet your problem remains the same:
You focus too much on details, which unfortunately don't show up in the actual icon.
I have no experience working with PS, I always work with GIMP, which features a small preview. Aim for what looks good in the ICON rather than the big image. Most big images look "bad", but their icon versions work wonders.
Same thing with this icon of yours: The big image looks really icy, yet the icon looks undefined. I gotta say though, I myself find drawing ice/rocks rather difficult.
You could try what I sometimes do: check Blizzard's icons and use them as references. You will see how they worked with light sources etc.
Like Frost Nova: the ice itself is REALLY sharp and spiky, try to recreate this effect. Stronger highlights would also make this look better.
Though this is just my humble opinion. It's really interesting to see how everyone has his very own style.