More visual noise isn't necessarily a good thing; look at how many people complain about the enormous Nitrome explosion graphic. In a melee, you need to have as clear a view of what's happening around you as humanly possible, particularly when you're using an attack that's at its most effective when you're totally surrounded by enemies.

Besides, the Leviathan isn't meant to be spectacular; it's the easiest 5* sword to acquire, as the line's recipes are all 100% reliably available from Kozma, and it's a pure Normal damage weapon. It's a go-to, a reliable, dependable sidearm; the flashier-looking weapons are the preserve of harder-to-get alchemy lines and come with a more complex suite of advantages and drawbacks. Even they don't have much in the way of big, flashy attack animations - even relatively OTT swords like the Troika line restrict their cosmetic effects to a relatively small area where damage is being done by the weapon. A ghostly Knight manifesting over my head is just going to get in the way.

The Cold Iron Vanquisher is a tremendous waste of time and shouldn't be anywhere near your inventory.

We "transmuted" it, alchemy can't be perfect... :D

On the other hand, if we asked some factory to do it, perhaps we can demand a certain amount of quality from it, yet it would look worn down pretty soon anyway.

Well, if we're talking about equivalent exchange... you are asking for a better sword from a worse one. And don't go spouting off about mats and Energy; Maybe the heat makes your sword stronger, yet messes up your sword so bad that transmuting it makes it look as though it has already been used.

As for the cosmetic of the blade... Its a freaking Vanilla weapon! It was not meant to look awesome! Cool? Yes. Awesome? No.

Maybe bring back the ol' dragon thing? Chinese myths heavily involve Dragons with ANYTHING to do with water, so perhaps...

It would go:
Charge...full charge. Release, preparatory backswing for the spin releases a blue/transpatent dragon that follows your sword as you spin and moves outward slightly at the same time, highlighting the damaged area, then fades outward from your position.

At most, that is the most HEAVY plan I can think of. As in if people want to make it super cool (even when it's like the most common beginners 'I want it...' sword...), this is the best I can come up with, however cliche.

Although it would make it more of a 'Legendary Aqua Sword' than just your average 'Oh look a massive sword to hit things with.'

I mean, it's supposed to be just a plain sword as far as I can tell. But that's the absolute BEST I can give if anyone wants it.