That is nice! I really like it

I'm thinking it might be too blue.

I'm going to try Aeldari Emerald next. I thought it might be easy and different to make a War in the Webway ghostly Custodes army... with Sisters of Silence being the only "real" (read: not painted like ghosts)  people there.

Thinking:

Black primer

Runefang Steel

1:1 Contrast Medium + Aeldari Emerald

White eyes

White power weapon edges

Nihilakh Oxide around vents, joints, and decorative recesses

I'd was thinking perhaps some recess shading to really darken the shadows and then either an all over drybrush of runefang steel or that colour on the pauldron rims, halo, the rim of the shield and maybe the shield emblem.

Couldn't you use a wash for the recesses then drush brush on some white?

I could. I'm thinking that might work better. I'm picking up some more paints on Thursday.