There was no "30 year Saxon war", it was 32 years, and was less a war and more ethnic cleansing.
Charlemagne and the Roman Catholic Church spent 32 years killing Saxons for refusing to convert to Christianity.
Vlad Dracula is no more descended from Attila the Hun than anyone else in Europe, that was made up for the book.
Since he wasn't a vampire, he has no vampire brides. Couldn't climb walls, or turn into fog, and didn't have fangs.
The argument isn't even correct for the fictional character. Although there are 3 female vampires in the book, it is never said that they are Dracula's wives. He could control the weather, wolves, bats, and rats, and any human he has bitten (Renfield, Lucy, Mina), and can gain a certain level of control over those he's hasn't bitten. Dracula can also enter and control people dreams.
Compared to that "fangs" and being played by brilliant actors is just silly.
Charlemagne didn't standardise European currency. He simply changed the standard.
International trade had been established long before Charlemagne came to power, which is not possible without a standardised currency.
The entire Charlemagne vs Dracula is intellectually insane.
Dracula, Vlad Tepes, Voivode of Walachia, was a real person, not a fictional character, and has never been played by anyone in a movie.
When Leo is calling Walter to warn him about the police heading his way, the lock screen on his phone is clearly visible, indicating no call is actually being made.
Charlemagne ruled by force ("ruled by the power of the sword"), invaded countries solely to convert the people to Christianity (at the tip of a sword), and invented the Divine Right of Kings (Kings are chosen by God, therefore are entitled to do as they please). These are not things Leo would support, so it makes no sense for him to be arguing Charlemagne's side.
When Leo is explaining his proposed agreement for Vasquez and Alejandro, he says that if Vasquez is incarcerated due to testimony from Alejandro, Vasquez's share of the restaurant go to his partner (Alejandro). Isabel then says that gives Alejandro motive not to testify or to lie on the stand so he doesn't lose his share. In other words, Leo misspoke; the point is to make an arrangement to assure Vasquez that Alejandro won't testify against him so that Vasquez won't kill everyone, and the way Leo said it would just give him more motive to testify (complete control of the restaurant). Leo should have said that Alejandro's share of the restaurant would go to Vasquez if he testifies against him so that he's disinclined to testify.