Black market shops

i would think that vampires would have somekind of underground network, including places to buy weapons, armor and other necessities since the shops in the city are only open during the day... when the sun is out... vampires tend to not like the sun too much, it hurts their eyes... and skin... and everywhere... also there are some places you can buy healing potions... why not harm potions(which would work like heqling potions for vampires) and perhaps there could be different degrees of harm... like the inflict minor/serious/crtical wounds....

In vampire the rpg vampires can use their blood to heal their wounds. Why not give them a healing ability tied to their bloodpool? It would cost x amount of blood to heal themselves.

if it's not too over powering you could give vampires spell like capabilities that would be fueled by their blood pool too. and these spell like abilities could replace any currently exsisting bonuses. and they wouldn't count as magic but inate abilities... and the blood pool could increase with your level or age.