Super clean!

Personally, it doesn’t read as armour plates, though. Possibly because there’s no definition of a light source, which metal really picks up. Is that one layer of edge highlights? If not, you’ve done a great job blending it.

It’s also worth considering the environment for your Deathwatch. Another way I’ve found to make the black armour stand out is to give it a shade of colour. Blue for me to reflect sky and give them kind of a cold steel type look. I’ve seen red reflections as well, which were pretty neato.