More primals are coming in Patches 2.X+. If I remember correctly, the Gigas are the ones that will summon Shiva, and I think we've only just released them from aeons stuck underground. Give the ascians time to get some "paragon" feet on the ground and she'll be showing up soon enough. It is kind of silly that you can get crystals of light from mobs strengthened by dark powers, but there's probably something to it that I'm just overlooking thus far.

I think the answer to your question might just be that it's not the crystal of light for ice, but a crystal of light for ice.