Definitely Master for consistancy sake. I will put that.聖 can mean Saint also, so Bow Saint is a better fit. But you can name it Master for the consistency sake.
I really hate how the author put words, Sword Master by Kurena and Doberg also use this word, and the Demon General was an improvised word because the original word is like Demon God or something which sounds higher than Demon King the highest smh, Idk why the previous translator put Devil but nah for me.