"'χ'... A most ancient letter. Some say "kye", but the meaning is the same." Me, staring at the ancient Greek alphabet: Haha... I get it.

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"'χ'... A most ancient letter. Some say "kye", but the meaning is the same." Me, staring at the ancient Greek alphabet: Haha... I get it.
Also, since I'm thinking about it: how do the kids in BBS know the difference between the Keyblade and the χ-blade? It's not like they're pronounced differently. Logically, shouldn't their reactions to hearing about it have been something along the lines of "a Keyblade? Yeah, we all already have one..." instead of "what is the Key/χ-blade?" The only way they could've known that Ven was talking about something different from the blade they all carry was if they saw the spelling of it — which, given that it's a verbal conversation, they can't. Even with the way he says it, a standard reaction would've been something like, "Ven, we already carry Keyblades."
As much as Birth By Sleep's story is dependent on all 3 characters, the opening really frames Ven and Terra (moreso Terra) as the protagonists. Which is funny because out of the three, Aqua is the only one framed as a hero in-game, as Ven's mistaken for a thief a lot and Terra's an anti-hero in just about every sense.