Continuity mistake: When Scud is in his van looking to investigate a noise, you see a donut and a cigarette in his right hand, but when he turns on the lights, there is only a cigarette in his hand. (00:41:42)
Continuity mistake: In the scene where Blade and the Bloodpack go to the club to find reapers, there is a clip where Lighthammer and the girl go into an area by themselves. When it shows the two, the girl has a blue light filter on her gun, but when cuts back to her, there isn't any filter on it. (00:40:02)
Continuity mistake: When Blade meets the Bloodpack for the first time, everyone is introduced by name. When they introduce Snowman (the swordsman), he does a gesture with his right hand. In the very next shot where they show Chupa, Snowman's hand is already back to the handle of his sword. He may be fast, but he's not that fast.
Answer: In Blade I we saw that with sunscreen and the avoidance of direct exposure Deacon Frost and his lackeys could go out by day. The reapers are probably two or three times more sensitive than normal vampires so the exposure was probably not long or direct enough to kill the regular vampires.