Well, as far as I can tell, Rei is way more experienced and composed than the current lord, and generally seems to understand what's really going on around him, a true lord. I wouldn't be surprised if he was more powerful as well.
Oh... My... Gosh... Ragnarok. I just wet my pants from the amount of development in every chapter. I certainly do hope Rei will take it with him, that would be so... hawt~