Here is your chapter with the final suggested edits. I've bolded the changes for easy identification.
With both feet braced against one side of the mountain wall and his back pressed firmly against the other, Siqi slowly regulated his breathing, allowing his trembling legs a brief moment of rest. He risked a glance downward; from this dizzying height, Khawn, Nachin, and Khair had long since vanished from sight. The cold wind howled past, a frigid, piercing shriek that confirmed his grim estimation: he must be well over 150 feet above ground, perhaps even higher, for the wind here was chilling to the bone.
He knew that the longer he rested, the more the gnawing desire to quit would settle in. So, with a surge of willpower, he shifted his legs back into their precarious split position and began inching himself upward once more. After another 30 feet of agonizing ascent, he finally spotted it: a narrow cliff extending out from his left. A weary sigh escaped his lips, not of relief, but of grim recognition—the most difficult part of the climb still lay ahead.
He continued pushing himself; in his line of work, quitting wasn't an option. He knew he couldn't expend all his energy, as the hardest part of the climb was now only an arm's length away. With a final, desperate push, he reached up, his fingers scrabbling for purchase on the cliff face. To his surprise, above the narrow outcropping ledge was another, larger one that could lead him directly to the top of this section of Whitefang Peak.
Excitement surged through him. He hauled himself onto the first small, narrow ledge, then immediately launched himself upwards, grasping the second, larger one. With a final, supreme effort, he pulled himself over.
Reaching the top, he collapsed, utterly spent, onto the cold ground, which was dusted with light snow. He lay there, breathing heavily, watching the condensation mist from his mouth float briefly above him, then quickly evaporate. After a few precious moments, he knew his brief respite was over. He pushed himself up and began walking away from the cliff edge.
As he walked around, he found no good place to climb down the mountain; the side facing Gimsong Kingdom was a sheer, smooth rock face. He sighed, walked back to the outcropping cliff, and began writing down details to his best judgment. As he was tying the handkerchief containing his written letter and some small stones, a thought suddenly struck him: what if they tied a rope over the cliff and simply descended the mountain towards Gimsong Kingdom? He quickly removed the letter from the inside of the handkerchief, jotted down his final note, and tied the handkerchief tightly. Then, he walked to the edge of the cliff and dropped the self-made handkerchief pouch down the small gap.
Khawn, Nachin, and Khair waited for news from Siqi. They saw at the front of the small gap waiting patiently when something suddenly dropped down with a loud heavy bang that echoed in the mountain.
Nachin quickly scanned the area and found the knot-tied handkerchief on the ground. He picked up the knot-tied handkerchief, untied it and handed the written letter inside to Khawn.
After Khawn finished looking at the map, he looked at Nachin and said, "Nachin, you head up first. And you." He looked at Khair. "You go back and tell the others that Siqi had found a way up and not to leave any rope behind. We really need it this time."
By the time Siqi had secured the rope to the outcropping cliff, threw the rope over to the other side of this section of Whitefang Peak, and came back to double-check the secured tied rope, he saw Nachin's head approaching under the first outcropping cliff.
"Hey!" Siqi called out and his voice echoed. "On top of your head is a double cliff."
Siqi gritted his teeth, his muscles screaming as he hauled the heavy rope. He let it snake down the daunting, glassy-smooth, unforgiving mountainside, his heart pounding a frantic rhythm against his ribs. Even from his perch, he could tell the slick surface offered absolutely no purchase. A wave of cold dread washed over him when he realized the rope wasn't nearly long enough to reach the bottom. It only extended to a small, crumbling ledge far below, a precarious sliver of hope in an otherwise desperate situation.
He knew the army would be here soon. Crossing the mountain to the Gimsong kingdom by tonight was a desperate necessity, crucial to fulfill the task Chinua had given them. More importantly, Chinua's plan to take over Nue-Li City hinged on their success. As the army's personal scout, the burden fell on Siqi. He had to descend, to discover if there was any other way around this treacherous section of Whitefang Peak to reach the bottom.
He grabbed the rope, his knuckles white, and slowly began his descent down the unforgiving mountainside. Every inch was a careful calculation, but during the treacherous slide, he was profoundly grateful that all his brutal training on the eastern slopes of Whitefang Peak was finally paying off. His specialized boots found minuscule purchase, his muscles burning as he controlled his fall until his feet finally, mercifully, landed on the narrow, crumbling edge. From there, he stared down into the dizzying abyss that plunged to the very foot of Whitefang Peak.
From where he stood, he estimated a daunting 150 to 180 feet still separated him from the foot of Whitefang Peak. He looked up, and his gaze met Nachin's face, peering down at him from the ledge above.
Siqi looked up and bellowed, "Another 150 to 180 feet to go!" The words bounced off the sheer rock, his voice echoing mockingly across the chasm. The sound died, and then it hit him: this mission was a secret, and his careless shout might have alerted anyone nearby, jeopardizing everything. A wave of frustration washed over him, and his right hand curled into a tight fist as he lightly tapped his forehead, a silent reprimand for his foolish mistake.
Siqi watched as Nachin merely nodded, his expression unreadable, before withdrawing from the upper ledge a hundred feet above. Alone again, Siqi immediately scanned the sheer rock face, desperate for anything to secure his rope. He needed to descend, but the glassy surface offered nothing—no sturdy outcropping, no deep crevice—nothing strong enough to withstand a man's weight.
Siqi sighed, muttering, "I guess the only way was to keep extending the rope."
Just then, he felt something tap the top of his head. He quickly flung himself aside, then saw it: the end of a fresh coil of rope dangling beside him. He looked up, and relief washed over him as he saw Nachin already back at the upper ledge. Without a word, Siqi snatched the rope, stepping back against the cold mountain wall as Nachin expertly fed the rest of the line down towards him.
From where Nachin stood, he had a grimly clear view of Siqi as the sun began to sink. They both knew they had to get down the mountain before daylight completely vanished; descending this treacherous peak at night without a torch was simply too dangerous. Nachin kept his gaze fixed below, watching as Siqi meticulously tied the extra rope to the end of the original, then dropped it over the crumbling ledge. He saw the rope yank twice, a silent, reassuring signal. Then, Siqi's form slowly slid out of view, swallowed by the deepening shadows. Nachin's focus was broken only when Khawn's urgent voice made him turn back.
"Where's Siqi?" Khawn asked quietly, his gaze sweeping the empty ledge before settling on Nachin. He'd expected to see them both.
Nachin said, "He went down. The first rope was long enough to reach a ledge down the mountainside, so I sent my rope to Siqi. He's extended it to the foot of the mountain now. Siqi believes its final descent is another 150 to 180 feet." He looked over Khawn's shoulder and saw that ten soldiers had already reached the summit. "Captain Naksh and the others are here already?"
Khawn nodded grimly. He turned to two nearby soldiers. "One rope is not enough. Tie your two ropes together and wait for Siqi's signal."
"Yes, Captain!" the two soldiers said in unison, and they immediately began to tie their ropes together.
Just then, the rope descending this section of Whitefang Peak began moving right to left. Khawn quickly grabbed the rope and pulled it twice, letting Siqi know they had received his signal. It was safe to descend the mountain.
"It's clear," Khawn said, looking at Nachin. "You go down."
Nachin grabbed onto the rope, his movements deliberate, and slowly lowered himself to the side ledge where Siqi was.
Watching Nachin lower himself, Khawn turned to look at the ten soldiers who had already secured their ropes on the outcropping cliff. He also saw that Naksh and Drystan had made it to the summit.
"How is the situation?" Naksh asked, his voice sharp.
"Siqi just sent out the signal that it was safe to descend," Khawn replied.
Naksh surveyed the soldiers. "Ten soldiers go down at a time. We don't know how the weight might affect this." His eyes fell on Drystan, then on the stout rope secured firmly to the cliff. "You're the last one down. Once everyone is down, cut off all the rope. We won't let the enemy know we've crossed into their border."
Drystan let out a soft scoff. "You got it."