ΔE 21.1, loose: different enough that you should pick on purpose. Obsidian Black is noticeably darker, more saturated than Honed Steel.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Obsidian Black is noticeably darker, more saturated than Honed Steel.
The same difference applies the other way round: Honed Steel 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 Honed Steel on the colour wheel See Obsidian Black on the colour wheel
All matches: Honed Steel equivalents · Obsidian Black equivalents