There is a difference between a clear cut battle and societal difficulties. He’s definitely a coward, but it’s not unfitting with the rest of his character. He finds it much easier to fight monsters and enemy soldiers, as he has been raised to do. It’s uncomplicated for him. The i Tustin with his daughter is not. His lack of self confidence as a commoner and former slave didn’t go away even when he rose to a much higher and honorable position.
Revealing he is her father would destroy the very power he would need to support/protect her because of the oath of chastity that he broke (the punishment is severe, I think death?). It could also turn his political enemies into hers as well. There’s also a big gap between his reverence for Beatrice and lower perception of his own inherent worth.
Also, simply taking her away and raising her as an adopted child somewhere else or with him would require denying her royal blood, which he considers near sacrilegious. He wants her to experience all of the luxuries of royalty.
In the end, these doubts prevent him from acting, and she is the one who suffers for it.
Despite loving stories from this genre, I cannot seem to like this enough to even read past 17 chapters. This is really boring and the supposedly brave father lacks self confidence even when he is literally a war hero. Mf can't even accept his own daughter lol what a great strong man. Just stupid af and idgasf if he's scared of tarnishing his dead lovers image.