To the right of where it says Opens with: (icon) Directory Opus 9, click Change..., then select the bold "Directory Opus 9" item in the left-hand list and click Clear Default, then click OK.
If you now refresh your file display, you'll have the icon you want.
After doing this, double-clicking RAR files outside of Opus may no longer open an Opus window for them. (Inside of Opus should still be fine.) To correct that, in a way which won't affect the icon, follow this guide: HOW TO: Make RAR files open in Opus on double-click.