I like this, I think it has potential. May I suggest a few things? You could address the 'French Prince' as the Dauphin, since it is the French name for the heir to the throne and it will add a lot of authority/accuracy to your story. Also, choose a specific year/decade/century for the story and let the readers know when it's set. I find it helps me a lot both when reading and writing to know what year it is since I like to contextualise it, I'm able to think 'Ah, so it's before X happened but after Y'- that is if you're basing this on real history. If you are basing this on real history, then I know a lot about English medieval history that overlaps with Welsh history so if you ever need any wider context then I'm happy to help! If not then... carry on! :)