ΔE 14.2, fair: the same colour family, but not a straight swap. Steel Blue is noticeably darker, more saturated than Gray Violet (Luftwaffe).
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Steel Blue is noticeably darker, more saturated than Gray Violet (Luftwaffe).
The same difference applies the other way round: Gray Violet (Luftwaffe) is noticeably lighter, 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 Gray Violet (Luftwaffe) on the colour wheel See Steel Blue on the colour wheel
All matches: Gray Violet (Luftwaffe) equivalents · Steel Blue equivalents