ΔE 7.6, close: similar, with a visible difference side by side. Obsidian Black is a little darker than Stormhost Silver.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Obsidian Black is a little darker than Stormhost Silver.
The same difference applies the other way round: Stormhost Silver is a little lighter.
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 Stormhost Silver on the colour wheel See Obsidian Black on the colour wheel
All matches: Stormhost Silver equivalents · Obsidian Black equivalents