Ill do this in a bit of a stream of consciousness rather than my usual planned out posts (for what its worth). I will be going on the assumption of necros Becoming them, or else Eshval's Blessed. Obviously the latter would have to be weaker.

Constantly, slowly losing health, must drink blood to regain health, perhaps make them unable to be healed by any other means.

Unable to eat/drink anything but blood. Obviously blood in containers would need to cure thirst as well for them.

Turning into bats/ravens like an air shifter, probably bad idea to let them fight in that form however.

Hypnosis effect perhaps? I dont actually know what this does, but I know thieves have it. Give it a mind control poison effect too perhaps.

Blood Drain: Ambush with a cleave-like effect, chance to instantly kill them and make them a zombie-like vampire thrall. Perhaps make it like assassinate instead.

Vulnerability to holy, silver, light, and nature (wooden stake anyone?), but resistance to all else.

Cannot use vampire only abilities in direct sunlight. Perhaps make it worse, but you dont want people pissed they are useless half the time.

I feel they should be more melee oriented than magey, makes for more variety.

Fashion Crucifix: Like Pillage, I suppose, destroy an item to create an unholy crucifix that can do stuff.

Mist Form: Become mist, rendering yourself invulnerable to all but aoe light/holy attacks (are there any?) but are unable to attack or cast spells. Cannot use or go indoors while under this effect. Lasts until canceled. (Remember you are constantly and slowly losing health, so it cant last forever, and your opponent will be healing while you hang out. Also would fade at day since you cant go indoors.)

Ill try to think of more later.

I think the distinction between an Eshval-religion bonused vampire and a necro "becoming" vampire is a big one. A Become'd (becamed?) Necro Vampire would need to be significantly more powerful then the former, to be on par with Liches and Mummies (relative to the risk of the transformation, of course). Whereas an Eshval vampire shouldn't be much more then adding some vulns/resistances, and maybe some flashy tattoo-emote stuff, ie some kind of life-draining attack, like a nerfed Vampiric Touch.

As for the necro vampire, I certainly like the idea of making it melee focused- giving the necromancer third attack and possibly enhanced damage would be appropriate, I think, but at the expense of some of his spell casting abilities- maybe removing some of his spells (Crimson Scourge, say) or limiting the size of his undead army, to avoid too much combat prowess. Alternatively, make it so the vampire cannot order his mobs to rescue himself, maybe all vampires are hubristic (apparently it's a word) by default?

Just some quick comments