Dies Mercurii, Mercury's day, became Woden's day among the Germanic peoples, preserved in English as Wednesday, through the same interpretatio germanica that turned Mars into Tiw. Woden, known more widely in later Norse sources as Odin, was matched to Mercury less for a shared portfolio of commerce and communication than for a shared role as a guide who moved between worlds, Mercury as psychopomp leading souls to the underworld in classical myth and Woden as a wanderer associated with knowledge gained by crossing boundaries others could not.
The French mercredi keeps the Latin planet directly, in the same pattern followed by mardi and vendredi, while German took a third path entirely with Mittwoch, literally mid week, abandoning the planetary reference altogether in favour of a simple positional name; English and the Scandinavian languages, by contrast, kept Woden's name in the day. The three different outcomes for essentially the same starting point, Latin retention, Germanic god substitution, and abandonment of the reference entirely, show that interpretatio germanica was never a single uniform process applied identically everywhere it touched the planetary week.
Sources Norse Mythology: A Guide to the Gods, Heroes, Rituals, and BeliefsJohn Lindow with Deutsche MythologieJacob Grimm