ΔE 14.3, fair: the same colour family, but not a straight swap. Arcane Gold is a little lighter, more saturated, warmer than Runelord Brass.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Arcane Gold is a little lighter, more saturated, warmer than Runelord Brass.
The same difference applies the other way round: Runelord Brass is a little darker, more muted, cooler.
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 Runelord Brass on the colour wheel See Arcane Gold on the colour wheel
All matches: Runelord Brass equivalents · Arcane Gold equivalents