Otherwise, I have to agree–there have been an awful lot of dark lord sacrifices of hapless virgins/children/whatever as openings, especially in prologues to RPG fantasies. This is actually a tough way to hook a wide audience–we don’t know the characters and have no stake in the story, so opening with the POV of someone who’s going to die a disgusting death a page later is a tough way to hook many readers in.

Punctuation first:

1, You need a comma after “altar.”
2. You need a comma, not a semicolon, after “bound.”
3. You don’t need the comma after “dagger,” but could leave it in if you really want it.
4. Lose the comma after “darkly clad man.”
5. Lose the comma after “hilt.”
6. Lose the commas after “the” and “yet” setting off “as yet” from the rest.
7. The word “unawakened” is unhyphenated.

That’s the painless stuff.

Less painless: You have a “dark form” with a “dark visage” who is also “darkly clad” worshipping a “Dark Lord.” Accessorizing in your god’s favorite color scheme is fine, but does not excuse an author using the same word over and over, especially when it’s not a specific color.

A “visage” is also a “face.” The only way a visage is holding a dagger aloft is if it’s holding it in its teeth. Given the following invocation, human sacrifice, and hilt-kissing, that makes the feat even more impressive. It’s like dark priest meets Cirque du Soleil. Don’t do this.

If all the sacrifice can see is a “dark form,” how can she see that the dagger is “ornately etched”? Special spotlights positioned over the altar?

Also, if she gasped when she sees the dagger, why doesn’t she scream or at least gurgle when she gets stabbed?

Also, if she’s pre-pubescent, why does she have a “bodice”? Such tops are usually for women who have breasts, which she won’t have yet. Moreover, why have a bodice if you’re going to have to cut through it? It’s not that the Dark Lord is going to be upset by naked girlie chests, even if censors might.

Beyond that, you obviously haven’t been doing any actual virgin sacrifices. Where’s the blood? The spurting blood? There should be a huge fountain of it. Actually, fountains if he’s not only slitting her throat but performing a hysterectomy.

There’s also a silly bit of bathos going on with the genteel luridness of the “unawakened center of her sexuality” followed by high school biology textbook “ovaries,” “uterus,” “vagina” and “buttocks.”

You also failed to mention that the altar was tilted or that it had convenient rivulets like a carving board to catch the spilled blood ready to pour down into the cauldron.

Also, what is he doing with her ovaries and uterus? Holding them in his hand? You didn’t mention a tray or anything, and speaking as someone who’s deboned a turkey, it would be a real trick to get those out with only a dagger and no assistance, even if he’s not doing it with the dagger in his teeth. Besides which, unless the girl has Heinz ketchup for blood–and even then, I’d doubt it–there’s no way the “dark form” is going to be able to remove the ovaries and perform a complete hysterectomy before the first drop of blood hits the overheated cauldron.

This doesn’t even get into the viewpoint problems where you start out in the girl’s viewpoint then go to an omniscient narrator. However, the big problem is that, while sword and sorcery sacrifices of virgins to dark gods can be done, it has to be done in such a way as to dazzle the reader and get him ready to cheer the hero, get ready for the appearance of the awful dark god, and all the rest of the assorted fun. This isn’t doing it, for all of the above reasons. And come to think of it, I was just looking up one of the best throat-slitting and cauldron scenes ever for personal reference before I even had a chance to read this. Here, see how it was done a couple thousand years ago. And this is just Bullfinch’s summary:

When she returned to Thessaly, Medea erected two altars, one to Hecate and the other to Hebe, the goddess of youth. She sacrificed a black sheep, pouring libations of milk and wine. She implored Pluto (Hades) and his stolen bride that they would not hasten to take the old man’s life. After Aeson was led forth, Medea threw him into a deep sleep by a charm and laid him on a bed of herbs, like one dead. Jason and the others were kept away from the place so that no profane eyes might look upon her mysteries.

Then, with streaming hair, she thrice moved round the altars, dipped flaming twigs in the blood, and laid them thereon to burn. Meanwhile the cauldron with its contents was got ready. In it she put the following: magic herbs, with seeds and flowers of acrid juice; stones from the distant east; sand from the shore of the ocean; hoar frost, gathered by moonlight; a screech owl’s head and wings; and the entrails of a wolf. She added fragments of the shells of tortoises and the livers of stags – animals tenacious of life – and the head and beak of a crow which outlives nine generations of men.

These, with many other things “without a name,” she boiled together for her purposed work, stirring them up with a dry olive branch. Behold! the branch when taken out instantly became green and before long was covered with leaves and a plentiful growth of young olives. As the liquor boiled and bubbled, and sometimes ran over, the grass wherever the sprinklings fell shot forth with a verdure like that of spring.

Seeing that all was ready, Medea cut the throat of the old man, let out all his blood, and poured into his mouth and into his wound the juices of her cauldron. As soon as he had completely imbibed them, his hair and beard laid by their whiteness and assumed the blackness of youth. His paleness and emaciation were gone; his veins were full of blood, his limbs of vigor and robustness. Aeson was amazed at himself and saw that he was now as he was in his youth, forty years before.

That’s how you slit a throat with style and panache.