At the end of Part 1, Katsa is brought in front of King Randa for disobeying orders. She proceeds to tell him that she's not going to work for him any more, she won't consent to being imprisoned or killed, and exactly how she will deal with the 200 royal guards in the room if they try.
Katsa's final encounter with King Leck, considering the circumstances, is epic.
Quickly followed up by Bitterblue's defense of her:
Bitterblue: [draws her blade] You will not hurt her. She did right. ... I'm perfectly well now that he's dead. And I'm not a princess. I'm the Queen of Monsea. Katsa's punishment is my responsibility, and I say she did right, and you will not hurt her.
The very first thing we see of Katsa is her knocking out dozens of guards on her own, without them knowing who she was. She then proceeded to knock out Po, even with the advantages of his Grace. And finally managed to get the prisoner she was rescuing away and safe, all on her own, all without being discovered.
Bitterblue, a small midget child, with a knife the length of her arm. That is all.
Bitterblue and Katsa crossing Grella's Pass, with Katsa pushing the very limits of her Grace to keep herself and Bitterblue alive and Bitterblue pulling her weight and even saving Katsa a few times.
Fire riding out and distracting the monsters at Roen's keep by essentially being bait. Her reason? Saving 50 soldiers with a commander who just threatened her the day before so that they can leave to help a city in need.
Fire keeping track of every person at a ball, controlling choice people and at the same time transmitting information to her allies.
Whenever Bitterblue appears in her judicial court, she or somebody else does something awesome:
Bitterblue ordering that the inhabitants of an entire street should be taught how to read after learning that somebody there is illiterate.
Bitterblue pardoning a mentally man because nobody should be punished for a crime they committed while not in control of their senses and ordering that everybody in prison should get checked by her personal doctor.
Po charging in and providing an alibi for Saf on Bitterblue's behalf.
Bitterblue's speech to her secretaries after she learned of their betrayal and cover-up is a powerful moment. She tells them though they lost her trust, she forgives them and believes they can earn her trust again.
