Sokka saw the last guy working his way towards Toph at the very last moment - too late in the end - as he used some sort of harness to attack from the ceiling and accost her with a knife. The moment of Toph's stabbing seemed to slow down in Sokka's mind, and he heard himself warning her in slow motion just as he saw the agent pull out the knife whilst slamming into her at a breakneck speed. He had time in the stretched moment to glance towards the last two fighters standing, the bending musicians, but his glance caught them just as they were both caught by chi blockers that had dived in on harnesses like the one Toph's assassin was using; the firebending woman fought back, but the chi blocker pulled a knife on her and brought her down with a swipe of the knife up her waist. Sokka's feet had been closing the small distance between himself and Toph as he witnessed the demise of the two remaining benders, and by the time he had turned his head to face her again, his instincts had brought his arms around in a deadly swing until his sword was sitting at the throat of the man who had his hand wrapped around the knife sticking out of Toph's back.
"Let go of the knife, or I slit your throat right here," he growled.
The man chuckled. "What about my chi blockers, Chairman?" he said teasingly.
Without looking behind him, Sokka pulled his boomerang out of its pouch with the hand not holding the sword steady at the man's throat, and threw it behind him with practiced aim. He didn't really know if it would reach the advancing chi blockers. All he could think about was getting this man away from Toph, before killing him for hurting her.
"Forget about them," said Sokka. "You get away from Chief Beifong now, or you get to know first-hand why I am the best swordsman in the world."
The assassin let go of the handle of the knife handle that was protruding horribly from Toph's inert lower back. "Gong Li sends his regards," hissed the assassin, and grasped the edge of Sokka's sword, slicing open the palms of his hands, and slit his own throat before Sokka could do much more than gasp. He felt something sharp glance off the back of his neck and heard two thumps behind him. He turned in response, and his boomerang came whistling into his hand as he instinctually raised it for the catch.
The two chi blockers had fallen within ten inches of him.
Sokka got down on his knees and cradled Toph in his arms with trembling hands, struggling to get a grip under her back where her blood had pooled. His head swam, and he realised that the graze on his neck must have been a tranquilizer dart that mostly missed.
"Please, Toph…" he said, unaware that tears had begun streaming down his cheeks. His voice was very loud in the eerily silent ballroom. "Please be okay."
With the hand not supporting her back, he checked her neck for a pulse, unintentionally smearing blood on her paler-than-usual skin. It was faint, but there. He wanted to try and wake up Katara, get her to heal Toph, but all of a sudden Sokka's limbs felt weighed down with lead, and he was struggling to keep from losing his balance. Darkness closed in around the corners of his vision, and the last thing he said before losing consciousness completely was her name.