ΔE 10.6, fair: the same colour family, but not a straight swap. Grey Blue is a little lighter, more saturated than Dark Elf Shadow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Grey Blue is a little lighter, more saturated than Dark Elf Shadow.
The same difference applies the other way round: Dark Elf Shadow is a little darker, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Dark Elf Shadow on the colour wheel See Grey Blue on the colour wheel
All matches: Dark Elf Shadow equivalents · Grey Blue equivalents