I wouldn’t suggest you change your writing regardless of how Swigian places. Your choice of subject matter muddies the water regarding your experiment, I think.
[spoiler]For one, you’ve got a neat bit of discovery where you realize that you’re Grendel. That’s a cool moment.
For another, you’ve then got outside-the-game text doing the heavy lifting of setting and purpose. For people familiar with Beowulf, they can lean on it to fill in the lacunae your prose left behind. It’s like how fanfic can lean on what you already know about the work being, er, fanfic’ed. If you weren’t riffing on existing text, I expect the results would have been very different.
For a third, the sparseness worked with your chosen character. Of course Grendel will be oblique and gruff. Your chosen text makes your prose a deliberate artistic choice instead of a social experiment.[/spoiler]