Kharn vs Celestine:
Khârn revved Gorechild and clashed the axe's haft against his chestplate. Then he looked up, past them, and let out a long, low growl.
'The angel…' he rasped.
Celestine swept down, swinging her blade in a fiery arc of judgement. Her strike met Gorechild with a resounding clang, and Khârn was driven aside. Celestine hammered the Betrayer's guard with a blistering string of blows, darting, stabbing and hacking, driving him back step by step.
As she did, Kassar and D'sakh found their feet. A'khassor knelt over Skarle's fallen body, his reductor whining as it cracked open the fallen warrior's chestplate to extract his gene-seed.
'Do we shoot them?' asked Haltheus.
In that moment, Celestine shot a look back, over her shoulder, straight at Kassar. Her face was unreadable, but her intent was as clear to him as if she'd spoken aloud.
'No,' said Kassar. 'No. Exfiltrate.'
Leaving Skarle's fallen body, the last of the Unsung ran for the eastern arch. They passed the fight ignored; Khârn cared only about the angel he fought, and she sought only to hold his attention for as long as she could.
Bursting through a billowing crimson fog-bank, Kassar saw the arch ahead of them. A scattering of cultists stood in their way, ripping and battering at the fallen remains of a penitent engine. The Unsung fired a tight volley, blowing the mortals off their feet, and swept through the archway into the corridor beyond.
Celestine fought with speed and skill. She fought with determination, and a desire to see her enemy fall. Even though she knew that he wouldn't. Even though she knew that for her, this path, this incarnation ended here.
She was satisfied, for the Emperor's will had been done in this place, but she wept golden tears, for as the beacon's light went out, so the Tsadrekhan Unity would wither and end. Already she sensed the shadows gathering, the storm growing worse, darkness rushing in from the void to fill up the absence where light had lived. Billions were about to die, or worse.
Yet the dawn could not come without the darkness. Day could not be born anew without first vanquishing the night. She knew this as surely as she knew that the Emperor had meant to see the beacon in the hands of Kassar and his brothers, rather than let it fall to the worshippers of Khorne, or Slaanesh.
It was a grim equation, a measure of how desperate the Imperium's plight had become, but Celestine trusted her Emperor. For thousands of years, across dozens of lifetimes, he had never, ever led her wrong. He would not do so now.
She had faith.
And so, as her strength failed her, as Gorechild's ringing blows numbed her arms and drove her to her knees, she did not despair. As Khârn smashed the Ardent Blade from her hands, and ripped the beautiful wings from her back, she knew only satisfaction for her task, and sorrow for all those martyred to see it done.
And as he swung Gorechild high, and struck her head from her shoulders, Saint Celestine felt only blessed release.
I am unsure if Celestine was at full power.