Context: Person R is talking about person F, how they don't need to test F on their growth in power and such. Then this line is said:
R: Fは私といたころよりも ずっとまっすぐな瞳をして―― 魔力も満ちあふれて。
R:F has a more straightforward gaze/look in their eyes than when they were with me…and F is simply brimming with mana.
Also F tends/tended to being less confident in themselves
I think R is trying to say that F is more self confident and such...