I realy love this. I think you really captured their desperation/resilience. I feel I can realy imagine the soldiers saying:"but captain, we're ridiculously outnumbered!" "Your point?" "What are we going to do...?" "We're going to kill them all."
Don't underestimate how important colour and shading are, they can make or break a picture, and can completely change its mood. I'm happy to say your colouring defiantly falls into the "make" category.
I have worked on my version of an Eldar codex that has created a warrior seer that is truly a combat psyker like the 2nd edition fluff had them. all offensive little defensive and dedicated to the shrine of the aspect they left.
That illustration in the newest Necron codex was an instant fav of mine, I love the newer Farseer/super-Warlock design of the guy in the middle. BTW, how do you know they are Ulthwe? I had assumed they were Alaitoc from the associated stories, or Saim Hann because of the dragon crest.
Ah crap, if they are from Saim Hann I didn't know, I didn't see the crest. I just thought it to be random given that on the page it's shown I don't think there are Eldar stories, only on the preceding and further pages do they talk about Eldar.
I didn't think they would be Alaitoc, since they would be awfully close to the enemy for such a ranged combat focused Craftworld.