I used to play club soccer and softball and while I am rusty from not playing in years, I’m still a superior player (no tea no shade, and not bragging) to others because of the rigorous training I put in years prior. The muscle memory never leaves, yeah I’m more tired, but that’s just because I’m out of shape, but the skills I learned never left. Also she’s probably on fight or flight mode because it’s war, so that probably makes up for her out of shape ness. Just my input!
Extremely wrong! She practiced since she was a kid, because she was a prince. Did you even read the manga properly? It was explained in the first few chapters that she excels in swordship. And it was emphasized so many times that she is that good with swords. And it was explained too that she practiced secretly so her ability did not get rusty. I forgot where, perhaps somewhere around the part when she defended the town. But she definitely said it, although it was not drawn by the artist. I think you should read properly instead if just skipping over and only look at the pictures.
if you are an artist or a sportsman, regardless of your accomplishments, without regular practice you are evidently going to lose the quality of your performance (saying from personal experience). But yes once u get out of your 'retirement' and start practicing you will reach your best physical level much quicker than a newbie. She has the emotions there, but you're comparing her performance as a child to that of a grown person? with that logic, no one needs to practice once they become a superior player.

She's has had 0 training since she was a kid, has given birth since, yes she may have some knowledge of things, but even if she was the most athletic person no way that physic would last bruh. At least have her practice in secret or sth. martial skills are gained not built in your genes.