Action crit #2: be specific!

------

"Saved?" his father replied from his place somewhere in the ranks of Herald's siblings, his voice deathly low. "Harbinger, show him what I think of his offer."

With a wild grin, his brother raised his sword high and lunged at the man.

Light flared across the courtyard. Herald threw up his hand, furiously blinking away the glaring after-effects. The faint smell of scorched flesh drifted on the wind. Just like when his newest sister, now the tenth youngest, had once attempted to walk outside. Sunlight. They'd brought the sun inside? But how could that be? They were meant to be safe in the shadows.

He lowered his hand to the sound of his brother's snarl. Harbinger had recoiled from the man, scrubbing madly at his face. >>who's this man?

The man's lips pressed into a grim smile. "So be it." There was a brief flicker of a small object as he tucked away whatever strange weapon he'd used and stepped into the shadows. Calmly drawing his sword, the man attacked the still distracted form of Herald's brother. >>again, who? 

Herald rushed forward to stop him, a cry of warning humming through his throat. >>a cry and a hum are very different things... which was it?

He was too late. The man reached Harbinger first and, with his brother still rubbing his eyes, the metal met no resistance as it slid into living flesh.

His brother stiffened. The hand dropped from his face. Mouth agape, he stared at the sword imbedded in his chest. Blood coated the blade sticking out the back, dripping from the point onto the dry ground. His lifted his head, gaze searching then locking with Herald's. He stretched a hand towards him. "Broth-"

No. Herald watched as the blue and whites of his brother's eyes turn black. All colour drained from the barely tanned skin, leaving it ghostly pale. If it wasn't for the dark stripe the shining object had left across his brother's face and the faint stubble adorning his chin, he would've been the exact image of their father; even the dark-brown hair looked black. >>the sword? or something mentioned in a previous scene?

"An unborn," the man hissed, eyes widening as he stepped back to stand on the edge of the shadows. There, he fumbled with the straps of his beltpouch. "So the legends are true." >>this guy needs a name or something...

Harbinger made no effort to answer the man, merely laughing as he fingered the sword hilt. The bleeding had stopped. Hauling on the bloody blade, he slipped it from his body as easily as it had gone in. In one quick move, his brother twisted the sword in the air and, before the man had time to react, dashed forward to jab the weapon up through the man's head. 

Herald stepped back from the pair. The tang of blood drifted on the wind, the scent wriggling its way into his nose. That grin ... The way it twisted his brother's face was not natural. With a giggle that sent a shiver down Herald's spine, Harbinger held up the corpse via the sword, wriggling the blade deeper into the skull until the slack jaw sat against the hilt. Herald shuddered at the grating of metal on bone. >>maybe you've established that Harbinger is really strong, but the human skull is tougher than this. "Jab" doesn't sound violent enough to skewer a skull.

He wasn't one to miss an opportunity to defeat an opponent, but he'd never seen his brother take such delight in mutilating a corpse. The most he'd ever seen Harbinger do to another was drink from the unborns back in hell. Despite the occasional failure, they took care not to kill humans, for his father did not like feeding from dead flesh.

With a sneer of disdain, Harbinger threw the corpse back out into the sunlight and turned to face his siblings. Behind his brother came the cries of horror as the man's companions learnt the full extent of his fate.

Herald hastened to his brother's side. Harbinger didn't appear harmed. Not where it was obvious. But what about his mind? What damage had been done there as he joined his father in becoming strigoi? "Brother-"

"Listen to them," Harbinger said, his voice high with more than amusement. He cocked his head, though the cries were anything but muffled. "Listen to how they mourn their leader's death, like orphaned goats bleating for their herd."

Silent, Herald stared into a face he was longer sure he knew. One look into those inky-dark eyes and the suspicion that his brother was insane fast switched to a surety.

"How strange." His brother's head twitched. Harbinger's eyes narrowed, the chilling gaze boring into him. "I can ... taste your concern." He gave a short laugh. "Do not worry so, brother. I am fine. I now have all the power and strength and freedom to do as I please." He clasped Herald's shoulders, fingers digging into flesh until it bordered on being painful. "You cannot imagine what it's like!"

"You're right." He stepped back, pulling free of his brother's grip. "I don't know." A handful of his siblings had suffered the misfortune of becoming strigoi in the past couple of centuries they'd been here. "And I don't want to." All of them had lost their minds. Many more had gone on to lose the remainder of their lives. And now you're dead. Dead, but still living. Still moving. Still feeling. Still feeding. He didn't want Harbinger to be the next one to share that fate. >>who?

"You don't get to choose, brother." His eyes were wide. Faint images danced along the glossy blackness. "Just one mistake, Herald. That's all it takes. One chance for your heart to stop beating and ...." Laughing, he spread his hands.

The flicker of movement over his brother's shoulder caught his eye. Two men crept forward, poleaxes thrust far ahead of them. Before Herald could utter a word of warning, the spikes jabbed through his brother's body. Harbinger snarled, pain twisting his face, banishing the madness from his eyes.

The men pulled and his brother staggered back towards the open gate. He clasped Harbinger's hand, trying to stop the men from dragging his brother out into the sunlight. His boots slid along the worn cobbles, heels grinding against the dust. >>Pronoun currently refers to Harbinger. And wouldn't he slide off the spikes from all the pulling?

Together, with his brother's strength, wounded though he was, they were enough to stop the two men. Herald tugged, pain flaring in his shoulder. They could halt the men, but not win. Behind him, he could hear the shuffling of his siblings. Were none brave enough to aid him? "Help me!" he screamed over his shoulder.

Beyond the barrier of shadows, he spied another couple grab hold of the shafts. The men hauled and regained ground. He fought to stay put. Keep his brother in the shadows. Harbinger screamed as he stepped into the light. His brother struggled, howling anew as his actions only caused the wounds to enlarge. >>isn't he being dragged?

His grip was slipping. He squeezed his brother's hand harder. It made no difference. The men were strong and kept the spikes pressed hard against his brother's sides. He needed his other hand, but he daren't relinquish his sword for surely the men would attack him. >>this pronoun currently refers to Harbinger. Be more specific about how they're dragging him. 

Ten seconds, he thought. We've ten seconds. Too short a time to bring his brother back into the safety of the castle. Even so ....

Sensing a presence coming at him, he glanced to one side. A sword blade, the steel glinting in the noon light and heading for his head. Herald ducked, his own weapon raised to ward off the blow. His hand slipped from Harbinger's grasp, the sudden lack of resistance throwing him to the cobbles.

Scrambling to one knee, he reached out, blindly seeking his brother's hand. A finger entered the sunlight. An unseen fire licked at his flesh. Teeth gritted at the sensation, Herald shoved aside the pain and reached further. A thousand tiny daggers stabbing at his palm would've hurt less. >>what happened to the guy who distracted Herald? Why's Herald reaching blindly?

Sweat glistened off a face agony had twisted into a sick parody of itself. Harbinger fought to clasp hands. Their fingers briefly touched, missed and touched again. Then .... >>be more specific about why he couldn't grab his brother's hand. I don't see any reason that he couldn't.

Dust.

For a moment, one pure moment, his brother stood before him, brownish-grey ash replacing pallid flesh. Then a gentle breeze blew across the entrance, scattering the frail image over the men sprawled across the ground. Harbinger's clothes crumpled to the ground.

Herald stepped back, faintly aware of arrows flying by his head, the wind of their passage disturbing his hair. Men screamed as they were struck. The hot, heady scent of blood filled the air. Harbinger? Tears welled as he watched the gritty cloud that had been his brother dissipate. >>Herald was on his knees, last we heard. Also, I assume the arrows are coming from Herald's siblings, shooting at the people outside, which makes the next paragraph confusing. The siblings wouldn't go into the deadly sun to grab the fallen clothes, and I don't know why anyone outside would brave arrow fire to grab them? 

Hands grabbed him, hauling him further from the entrance. No. He shoved the people aside and dove for the entrance. There had to be something left. Some small piece of him that could be revived. Brother. Men fell over the clothes. Blood seeped from their wounds, soaking into the ground. Mingling the dust into the age-compacted dirt. Dust to stone. It was no different here. They hadn't escaped hell. They'd brought it with them.
-----

Green highlighter marks words and phrases that could be stronger and more visceral. Mostly, your word choices are pretty good, but the vague/generic stuff comes in clumps here and there. And this "the man" needs a name, even if it's only one that Herald gives him. "The man" is vague and generic, too. Be specific.

Another point: Herald doesn't seem to do much until Harbinger's being dragged away. Maybe you've established why already in the story, but it comes across as not caring too much.