Things that made the film flawed or ruined it
What happened to Karen from the first Blade?
Karen should of been in this film and had more of a relationship with blade, she should of been the new inventor with weapons and serum hopefully she will return in the fourth film
(While it's never explicitly stated, Blade is seen with a large supply of Serum, in much smaller bottles from the first film. The amount of these he has suggests he does not need to increase his dose - Chances are, once she developed this, Karen left - either to return to a normal life, or to join another group (like the ones in the third film).
How is Whistler alive in this movie if he died in the first?
He should have been a villain a vampire and he has to kill whistler to bring peace to him just like he did his mother