Promising idea but the execution is mediocre at best. The inconstancies and lack of thought kills this story for me.
MC in the first two chapters is portrayed as warmongering, cold blooded and having means justify the end approach. With is completely contridactory to her experience as a child. Granted the training could suppress these emotion but then why she have so clear memory and attachment to them after reincarnation? Everything is thrown out after reincarnation. There isn't even a one chapter where her mentality shifts.
The way how she gain access to the prince is also baffling why even put so much attention to this one knights? Ok she could have important information but after her amnesia it is not important. Even her skills won't be that important in this world. She reincarnated from the modern world. She have no idea how to fight in a medieval battle. As a spy, she don't know local customs etc., only thing that she would be good at is CQC.
Basically I was expecting manhwa version of Tania the Evil and get a mediocre manhwa.