So that those of us who don't speak Japanese can get a feel for what you're saying - what do the original Japanese texts mean (i.e. could you give us a better translation)?
でしょう roughly means "don't you agree" or "I agree", I didn't play the FF games so I don't have enough context to translate its original meaning here.
手に入る literally translates to "put into hand", but it means "acquire" in the context of opening a chest and finding a potion. Japanese games say "potion put into hand" and English translations say "You received a potion".
全く literally means "truly" or "very" but a lot of the time people use to mean "seriously" in a sarcastic sense. Like, "seriously!?" or "jeeze!". A beginner would think "very" but somebody with experience would know they're just complaining in a way that doesn't elicit* a response.
re: でしょう, without seeing the original Japanese, my guess is that a more atural English translation for your first example would be "Your brother is supposed to be a man, right? He's supposed to be an adult, right?" or something more along those lines.
Mato's translation comparison doesn't cover this line, so I can't easily link to the full context, but this is a young girl (Rydia) scolding an older man (Edward/Gilbert) for being too overcome with grief to take action. In the original US translation, the dialogue is "Crybaby! You are a man! You are a grown-up! You are not the only one who has lost loved ones!" The more literal translation would be "Aren't you a man?" but the meaning is the same.
"Brother" seems to be coming into it because Rydia is addressing Edward as "o-nii-chan". Pretty classic example of something that you couldn't translate accurately without knowing who the characters are.
"o-nii-chan" is a great example of translation difficulty because it's very natural in Japanese to refer to your older brother as "o-nii-chan" and it sounds like bad exposition writing in English.
And in this case it's just being used to address an older but not elderly man, in a way that's totally normal in Japanese but would be utterly bizarre in English.
