Here's the deal. We don't know the Elsecaller oaths. That could be shaping what she does. She's been been willing to if not already killing people for years trying to keep her family safe and together. (See the beginning of WoR) She seems like a mix of the Wind runners and the Sky breakers: driven to protect, but not those she hates; thinking dispassionately about the right, just way, (see her deciding to kill Renarin and the thugs in the alley) yet not going through with the Renarin murder, thus violating her own logical morality.
Her oaths could be affecting her, but another theory is this: she's awfully good at the whole logical, scholarly approach to morality, but when she needs to get her hands dirty actually effecting her cold, calculated plans, her conscience gets in her way, and she can't do it. This also would make the Amaram/King T parallel moot. Whom has she killed up to this point not in self defense (ish)?
WAIT. Did I just I ply that Jasnah has a CONSCIENCE? Mind blown!