I don't know a thing about this incarnation of Jack the Ripper, so the best I can do is speculate.
That said, does Jack have a way of overcoming Dio's regen? That aside, does anything stop Dio from simply flash-freezing Jack on-contact? Just glancing at the link, it seems like Jack just has less in his arsenal, not that his physicals are far below Dio's. I think he lacks the utility and pure destructive power to take out the Vampire.
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