I don’t speak French but from the examples you provided I get the impression that fracture is passiv (it happens to someone, like breaking an arm) and fracasser is active (so someone breaks something, maybe even on purpose, like the glass).
The sé at the end of the conjugated form fracassé reminds me of Spanish verbs where the reflexiv pronouns are directly added to the end of a verb. So if I would assume this to be the case here, too, and approach the sentences provided in a very naive (and probably wrong) manner, I would read
- Il a fracassé le verre avec un marteau.
as
- He is breaking himself the glass with an hammer.
A similar example for Spanish was discussed here
As both are romanian romance languages this might be a shared feature.