How are you capturing your images that you have only translation?
ICE does not have a pure translation mode. The closest that you can get is setting "Camera motion" to "Planar Motion 1" in the bottom left of the ICE window.
Even if the images are purely translating the ICE pipeline will still resample the images, which will result in the same slight blurring of the image as rotate would induce. I say slight because ICE is using a good resampling technique (bicubic
sharper - in Photoshop terms). I'm surprised that you are seeing noticable blurring vs. your input images. It would be interesting if you could post the input and output images somewhere to show us the
blurring effect.