ΔE 15.6, loose: different enough that you should pick on purpose. Natural Steel is noticeably darker, more saturated than Broadsword Silver.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Natural Steel is noticeably darker, more saturated than Broadsword Silver.
The same difference applies the other way round: Broadsword Silver 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 Broadsword Silver on the colour wheel See Natural Steel on the colour wheel
All matches: Broadsword Silver equivalents · Natural Steel equivalents