The syntax has morphed from Germanic languages, but with Norman vocabulary. Norman was a dialect of French from before the standardization of l'Académie Française.
France is sort-of at the crossroads of Europe, so it's no surprise that there's a little bit of everything in the French language. This is particularly visible in place-names of Normandy [2].
[1] https://en.wikipedia.org/wiki/List_of_Indo-European_language...
The Germanic core still generally gets used by all in high stress environments.
And yes, certain situations do tend to favor the Germanic portions to include especially coarser words.
Under fight / violence / battle conditions, the active vocabulary is Germanic, and not lacking in expressive power, nor subject to misunderstanding.