(( Wow, can't believe I missed this. o.O Can I make a few recommendations if you wouldn't mind?
And most of these ideas I got from White Wolf's popular Vampire/Hunter series.
Vampiric super-strength and such rely on there infected blood, right? Perhaps a stake to the heart should weaken them, as it stops the blood flow. There super-blood not being able to flow through there veins in the state.
Another idea I liked in there Hunter Venue was "True Faith". It allowed a rare few humans to stand on even (or even greater sometimes) ground than Vampires. They had such amazing faith in there deity, be it God, Allah, Mohamed ect, that they were able to shield themselves from physical or mental injury, and even perhaps deal physical damage.
Some think that it is actually the power of the human mind, rather than a deity, that unlocks this power, there extraordinary faith opening previously sealed aspects of there brain.
This also made them capable of resisting feeding attempts by Vampires, able to project a powerful aura to repel them.
Though you would probably want to change some of it around to fit this story better.
I think some of these concepts would be cool for characters. ))