Actually I don't think that's it because we can see the high priest smiling at the end plus she said there was something weird with the atmosphere when the priest told ML to calm down so I think he exerced some "mind control" I guess (also i'm sorry for any grammar mistake, english is not my first language)
Yeah, because when he "blessed" her, she smelled something and then soon after felt calm/confident (possibly due to the lady's blessing, but idk). Maybe he mourns his lack of light power to cover up that he has some other ability which affects people's mental states.
I think ML here did the right thing he is trying to make the temple people confuse since FL didn't die when her wrist was held, the temple people probably hunch about the location of her core stone and they also know that it was showing off and not hidden therefore making her very vurnerable, so ML being so "calm" against the temple's excuses will throw confusion on where is the FL's core stone really was, and will get rid of the idea that ML and FL are suspicious of them. Just a hunch tho, but I think FL's death will greatly benefit Deborah in the future cause I really think FL is the reincarnation of the saintess thus killing her, the temple might've have a way to pass her power to Deborah, and since Deborah is an ally of the temple, joining hands with ML's Son in the future will give the temple the influence they'll need to fuel their hunger for power ╮(￣▽￣)╭