Okay, I have to admit "Lord of the Flame" made me giggle in a way that was completely unrelated to extreme religious sects.

I love the idea of it having something to do with fire, and since the burns are so important, that might be why it seems to be something.

So why not translate something like disciple, disciplined, determined, with fire, ember, ash, and perhaps student or pupil. That these are going to be the things that pull this devoted person ahead of the others in the sect. Because the Fire-Disciple could work, but I'm not sure how the translations go.