The Outdoor Research Incandescent is a smartly featured light parka. In our experience, it proved to be an excellent ice climbing belay parka. At 17.9 oz. total weight, and with 7 oz. of 800 fill down, it is both lightweight and extremely packable. The Incandescent is certainly not as warm as many of the other parkas we reviewed, but for moving quickly, and when appropriately layered, it performs very well. And added bonus - It stuffs into its own pocket and clips to your climbing harness. A big plus for multi-pitch ice.
If you're looking for more down in your light parka, consider the Feathered Friends Hooded Helios or the Brooks Range Mojave both of which are very warm for their weight. The Rab Infinity is also a very comparable jacket.