It’s kinda cute of Shara to assume what she does in panel 1 is really threatening to the Captain.

↓ Transcript
<Shara threatens Slania with her knife>
Shara: So, CAPTAIN. What you're telling me is you're either CORRUPT or BAD AT YOUR JOB, eh?
Katharina: S-Shara? Don't you think we could maybe ... USE SOME HELP RIGHT NOW?
---
Shara: We don't need her help! She'll either betray us RIGHT NOW or shove us into a cell LATER!
Katharina: But she's the GUARD CAPTAIN ... !
Shara: Do you still think that means anything?
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Slania: ... look. I admit this is not a good look for the Guard. I'll deal with that LATER. But right now my witness is IN THERE and IN DANGER, correct?
Katharina: YES! We have to save him! ... will you help us?
Slania: You'll need to tell me what you know.
---
Katharina: ... Shara?
Shara: ... ugh. FINE. But don't you dare blame US afterwards!
---
Slania: Don't worry. My people, my fault. MY BLIND SPOT. I'm gonna help you.