ΔE 17.6, loose: different enough that you should pick on purpose. Summoning Sickness is more muted, cooler than Retributor Armour.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Summoning Sickness is more muted, cooler than Retributor Armour.
The same difference applies the other way round: Retributor Armour is more saturated, warmer.
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 Retributor Armour on the colour wheel See Summoning Sickness on the colour wheel
All matches: Retributor Armour equivalents · Summoning Sickness equivalents