I think, in the terminal messages, I can see a small ocular implant on his left eye. The first image on Terminal 1 of This Side Toward Enemy, especially, it pops out at me.
I thought to look at this while reading the Facts and Puzzling Things About... page for the impromptu leader of the human forces on the S'phit homeworld.
If I'm not seeing things in the garbled mess that is the left side of Blake's face, his ocular, unlike his men's, is smaller and more compact, only showing as a dark colored replacement for his eye.
The Blake chapter screen also shows that his left eye is very dark, and, if it's to scale, his iris (if it's an actual eye) is absolutely massive and dark, especially in contrast to his right eye.
Evidence that Blake is, perhaps, a proxy for Durandal? It's possible that any kind of storage implant would require a smaller ocular implant to fit the storage units (I assume that Durandal is smart enough to plan for a contingency like this, and make a backup of himself that would automatically re-upload and activate itself to more functional hardware when the coast is clear, and also that he would put the backup in the human with the greatest chance of surviving).
Or perhaps I'm just [?rampant] and trying desperately to be productive and contribute.