The judgment

Idira's long lasting animosity towards Argenta was the only reason why the fallen Sister was not already dead.

"I remember your words." Idira spat, as Argenta futilely struggled to break free from her bindings "Your lies. You exalted the purity of the flame: a light for the faithful, and a fire for the unworthy. I had to listen to this prattle so many times, that I was starting to fear even my whispers would end up screaming with your voice."

"I suppose that makes you an effective preacher, oh anointed one." Idira mocked. Argenta grimaced at the insult, but refused to comment on it. That was fine. Idira didn't particularly care about hearing Argenta's excuses. She just wanted to hurt her.

"But let us stop to consider the words of your dull sermons. 'The bearers of the holy flame bring the brightest of the lights.' Now, we can't have those living candles be of questionable purity, can we? And we can't have the heretics be decent folk either."

"Then how come you get to hide in the light, while I have to cower in the shadows?"

Disgraceful. To have your sins called out by such a sinner. Argenta hung her head in shame. Worst of all, the witch was right.
"You kept your guilt hidden beneath your gilded hypocrisy, and you still had the nerve to condemn me! I...I should tear you apart! You are just as corrupt as the heretics you burn!"

A personal insult, this time. The witch had just questioned her integrity. Whatever words of rebuttal Argenta managed to come up with died on her lips. They sounded hollow.

Idira paused her tirade to catch her breath. When she resumed, her voice was dangerously low.
"As you have judged me in the past, so I shall judge you now as well."

Argenta felt a lump in her throat at the mention of this new threat, as a dreadful sense of foreboding began overwhelming her.
"You are a self-centered coward who pretends to serve a higher purpose. You swore oaths of allegiance to your Emperor, and you broke them without a thought even after we welcomed you with nothing to your name. Lady Theodora offered you a roof, and you repaid her generosity with your treachery."

"Argenta, I am going to make an example out of you. On charges of treason, oath breaking and cowardice: I name you guilty, and sentence you to death."

A witch passing judgment upon a Sister of Battle. More than disgraceful. Unthinkable! Idira's sentence had been spoken with unmistakable finality, but she was not going to let Argenta die without one final insult.

"Any last words from the heretic, before I feed your body to the Beyond?"

Henrix van Calox did not try to stop Idira. The imperial law was no stranger to creative solutions, when it came to delivering punishment. If asked about the need to have a witch execute a traitor, the Interrogator could rightfully claim that, more or less, justice had been served.

The Rogue Trader had a different opinion. If we start killing each other, no one is going to get out of here alive. I need to rein Henrix back, stop Idira from using Argenta to repaint the walls, and secure the unconditional support of all three of them.

"Theodora didn't care about you as much as you think, Idira."

"What did you just say?!" Idira snapped, in an unimaginable display of impudence. No one talked back to a Rogue Trader.

"I am saying" the Rogue Trader replied calmly, in an attempt to divert Idira's attention away from Argenta "that your faith in Theodora is misplaced. She saw you as a commodity. A weapon. Not as a person."

"She brought me in on her ship when no one else would!" the Seer retorted "She fed me. She gifted me proper clothes. Above all, she trusted me."

Idira took a moment to recompose herself. Insulting a Rogue Trader was a grave blunder, one of the sorts that demanded a severe punishment. Anger would only worsen her position. "Lord Captain, when your neighbor claims she hears voices inside her head, would you put your faith in her counsel, or would you rather tie the witch to a stake and set her on fire?"

"The preferential treatment you received was not given out of benevolence." the Rogue Trader pointed out.

"Fine." Idira admitted "Maybe not entirely out of benevolence. But Lady Theodora acknowledged my gifts, and welcomed me into her retinue. I have been her seer and her enforcer, occasionally even a confidant. And what's wrong with that? I had to give something back, after all she had done for me."

Fool. She exploited you, and you are even thankful for it. Bah. Kind words won't lead me anywhere. I need to be blunt.
"Idira, you are still not seeing the extent of Theodora's manipulations. You were useful to her. Small gifts, words of praise, a sense of belonging...that was just the price to pay to purchase your loyalty."

The Rogue Trader then turned his attention towards Henrix.
"Master van Calox, I require your expertise in a specific field. When it comes to a psyker, could you remind us all of the benefits of being sanctioned?"

A broad subject, but from the way the question had been formulated, the Rogue Trader already had an answer in mind. The Interrogator's support was only meant to give more weight to an upcoming argument. And not a word more.

"Of course. You would not know this, Miss Tlass, but the act of sanctioning is a form of psychic stabilization. As you are well aware, the Warp is a source of power in its rawest form. By performing the act of sanctioning, a psyker sacrifices a portion of his ability to draw upon this well of unstable energy, and in exchange gains the restraints necessary to wield it in a more...controlled manner."

The Rogue Trader thanked the Interrogator with a nod.
"Indeed. And as Master van Calox pointed out, a sanctioned psyker is less affected by the physical and mental toll that comes by wielding such destructive power."

Idira blinked in confusion. The next words would have to be chosen carefully.
"Idira, Theodora was no fool. She had to have known that keeping you unsanctioned would shorten your lifespan."

And finally, the Seer was hit by the realization of what she had not wanted to see.
"But...why? Lord Captain, are you saying that Lady Theodora did this to me...intentionally?"

"I am afraid so. Remember that a Rogue Trader is, first of all, a merchant. Theodora saw potential in your ability to foresee the future, and took the necessary steps to secure this advantage for herself. She also knew that keeping you unsanctioned would further increase the opportunities that your whispers offered, for an even greater advantage."

"In other words, she traded your life for power."

Argenta fell to the ground, as the unnatural forces that bound her began to fade. She crawled on her knees to seek shelter behind the Rogue Trader, before the witch decided that she still wanted to get her revenge.

Idira made no attempt to stop her. She was too distraught to realize that she had let Argenta go.

"...what happens now?" she asked lamely.
"Nothing. There will be no punishments for today. But I wish to pass a judgment of my own."

A new judgment? In such a dark city, of all places? What could it even be possibly about?
Henrix, Argenta and Idira's attentions converged on the Rogue Trader, as they eagerly waited for his words.

"Theodora von Valancius was a terrible ruler."

Everyone stared. True, it was not unusual to have an heir denounce the crimes of a late monarch, but still...

"The planets formally under her authority were left in an abysmal state." the Rogue Trader continued "We had to travel for months, just to discover if there was anything salvageable at all from the division and heresy that ran rampant on these worlds. She surrounded herself with untrustworthy allies, and when they inevitably backstabbed her, she paid the price of her arrogance."

And now, let us put an end to this pointless bickering.
"Through her negligence, Theodora had nearly let her realm fall into ruin. She failed in her duties as a ruler, and she failed in her duties as an emissary of the God Emperor. In light of this, I believe that her death was a blessing in disguise."

"Which is why I am retroactively sanctioning her murder, thus absolving all parties involved in her death from punishment."

Henrix sighted in defeat "As the Lord Captain wishes."