I quite like your submission. Maybe they get too much Alpha Legion stuff? Or maybe the standard expected is just really high and they're getting a lot of submissions from people who always write as their vocation
Regarding the bolter thing, presumably the bolter rounds that tore away his vox and clipped his shoulder didn't detonate on impact? Bolters in the fluff are far more lethal than they would appear in the game, there's no way a human getting hit anywhere near the face would survive it- their head and most of their torso would be obliterated. Even a round clipping a shoulder guard would tear away the shoulder guard or throw the arbite backwards a few metres.