User blog comment:Western Gen/Speculations for Season 12/@comment-10990964-20140506205014/@comment-13690654-20140507073845

At the end of Halo Reach, your visor cracks. So, it's not quite impenetrable. I'm also inclined to believe he got a lucky shot, as if it was a regular thing for him he wouldn't have had a brief celebratory moment.