I was going to say that it was space not time, but then I realized her power could be Jikuu. Which makes her an FF5 time mage... I wanna see her Quick Leak someone in a red cone hat now.
Technically his luck stat grows on it's own. Plus he may not be messing with it because he doesn't know what it will do and all the other stats he understands their direct correlations.
Also he's a commoner. He's trying to keep him down because money/aristocracy reasons as well.
I thought this was one of those instances where they removed him from the party because they actually like him, but they don't want him to get hurt as they do progressively harder dungeons.
I don't think Esther is technically a trap. He's boyish and effeminate on account of being a younger child, and he doesn't lean into being confused for a girl.