Gunblade: It's not that bad. Although, to comment on Suspension of Disbelief, it doesn't work in the usual, logical sense. For example, most people think Cloud's jumping ability in Advent Children is ridiculous, but they can accept the Buster Sword. They're both equally impossible, & if Cloud is strong enough to wield that weapon, proportionally speaking, he'd be able to jump that high. But one is more unbelievable than the other. Suspension of Disbelief also works based on what is shown to be reasonable in the world. "It's not real" is often used to justify things that don't make sense, but fiction still has rules. I got a little disgusted with Fullmetal Alchemist when a certain character started turning shadows into blades & shit, because up until that point, everything that was manipulatable was made of matter. Shadows are not. Even though this shadow was special, it's still a stretch..
Buster Sword: It looks gay. Cloud gets much better swords throughout the entire game. I actually rued defeating Angeal in Crisis Core, because I knew it would mean I'd be using that piece of shit for the rest of the game. First Tsurugi was a much cooler weapon.
Masamune: I have to agree that it looks like it would be useless for fighting, due to its shape. However, I think it's one of the most awesome-looking weapons in the series, & far from the worst ever conceived.
Keyblade: I think it's a cool weapon. It's a magic key sword thing that's heavily tied in with the cosmology of the world. What's so bad about it? Sure, most of the weapons look gay, but then you start getting to ones like the Oathkeeper & the Oblivion. Hell, even the Divine Rose had an artistically badass look to it.
I was thinking maybe it looks exactly like the gunblade, except it's a keyblade.
