Okay, so this excerpt came from an interview with Nasu regarding his take and hypothesis on Ritsuka. Which is a pretty good read, tbh.
If there was ever a similarity between Ritsu and Kiomi, I think this is the closest that there is. Granted, the latter has a personality that's a bit more skewed than the former. She's not the type to be angry at evil for one, but she does have that "It'll work out somehow" attitude, no matter how dire the situation might be.
And while she can be self deprecating internally, has a lot of insecurities, etc. The most important part here is that she feels that it's her duty to survive. Sure, survivor's guilt was the primary factor for this, but time spent in Chaldea, getting to have servants and living with them gives her a constant reminder that if she dies, her servants wont last. And while there are other masters who'd probably be better than her (as she's mighty aware of what she can and cant do), she understands that her servants are comfortable fighting alongside her. And she would like them to continue fighting without being viewed as monsters after they show their true selves. She's not saying she's the best person to bring out their potential, no. However, Kiomi is the type to rally them and enable them despite the type of character they posses. After all, she hardly cares if one is a hero or a criminal, as she believes that each of them were products of their circumstances. Even if she isnt compatible with others, she does acknowledge them specially during the time when it counts the most.
Coz while I do play her as a person who seems to revel in things that one would perceive as evil (to the point where I joke about, if Chaldea was seriously entrusting the fate of humanity to someone who looks like she's 5 seconds into destroying it instead) at the core, she's a pretty good girl whose goodness wasnt allowed to truly shine through. She has her ideals of justice, warped by her awful experiences, and thus can be a little immoral/amoral in terms of executing solutions. If she grew up in the same environment as Fujimaru, I bet they'll have more similarities.
But she's also the type to appreciate people like Ritsuka, who she believes is quite brilliant because despite the things that they go through, they push on forward with everyone. Of course, she does worry about their mental state. The reason why Kiomi takes it upon herself to be the one to do the dirty work is because she doesnt want someone like Ritsuka falling prey to the cruelty of both life and the world.
"Of all things destroyed, destroying life changes a person."
Kiomi knows because she's killed someone before. You cant go back. And with Lostbelts, masters are forced to end human lives and civilizations. She always worries that each time leaves people like Ritsuka more broken than before. Even if we say things'll work out, just because it does doesnt mean it's the best outcome for everyone involved.