Not a standard English word; possibly meaning a scoundrel or rogue (from be- + rascal), but not documented in dictionaries.
Hypothetical: be- prefix + rascal (from French rascaille, ultimately from Latin radere 'to scrape'), but be- + rascal is not an attested formation.
This looks like how Shakespeare might have invented words—intensify an insult with be-—but by the time you'd say berascal, the language had moved on and we just use 'rascal' or 'blackguard' instead.
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