Runefang Steel vs Golden Shine

How close are they?

ΔE 50.6, loose: different enough that you should pick on purpose. Golden Shine is noticeably darker, much more saturated than Runefang Steel.

Can I use Golden Shine instead of Runefang Steel?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 51). Golden Shine is noticeably darker, much more saturated than Runefang Steel.

Can I use Runefang Steel instead of Golden Shine?

The same difference applies the other way round: Runefang Steel is noticeably lighter, much 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.