Ben 10 Radiant War, Volume 3.

The Father's Secret.

Author Notes-(The Video Game series Final Fantasy does not exist in Pavarti's world, but exists in the Sato City worl. Ben, and Erice's worlds also have Final Fantasy. Shi-Jian's knowledge of Final Fantasy primarily from engaging in Sato City's pop culture. Likewise the Multiverse is so infinite there is likely a world somewhere where at least 1 of the Radiant Seven has a TV show that is more or less accurate to actual events in their lives.)

Author's Science Notes (the Science of Nonsense in a fictional world)

-Sephiroth's sword if created in real life would not work well in real life. Even with Sephiroth's super strength and the blade weighing as much as a toothpick to him, it is highly impractical, with it's handle being made for two handed wielding in spite of Sephiroth using it for one handed attacks.  Overall the blade is so ridiculous that many weapons experts look at Final Fantasy with disgust. In FF7 Advent Children the sword fighting is often discussed on how terrible it is. Sephiroth utilizing the main advantages of a slashing weapon like Masamune incorrectly, the fancy twirling that only leaves you open.. etc. etc.  

Wow noncanon to FF7 as we are not Square Enix, the explanation is therefore thus in the multiverse of Ben10 Radiant War. Masamune was made to look terrifying and only to be wielded by Sephiroth. Sephiroth has therefore managed to invent a magic technique where he increases weight  and balance to the hilt of Masamune, allowing him to wield it one handed. The blade is also made of different Shinra Science secrets and magical properties, making it highly durable despite its unrealistic thin-length ratio.  Wielded by anyone who didn't know Sephiroth's methods would therefore find themselves wielding a wrist wrenching two handed weapon that would break their own wrists to block with.  In the end Sephiroth's sword was made with the goal of appearing terrifying and being only wielded by him as all SOLDIER weapons are in fact custom made and not standard issue (The Buster Sword was commissioned by Angeal's father who went into debt just to make it).  Sephiroth's sword techniques are not in fact Japanese (or in this case Wutai) style, but  Sephiroth's own self invented one handed sword techniques which would be better suited to a Longsword like that of Artoria Pendragon from the Fate Franchise. However, thanks to Masamune's Supernatural properties, it can take the punishment and power  of  the wrong sword style, while still taking advantage of its terrifying length.  Conclusively Masamune is NOT a good weapon even with this explanation provided, but it serves Sephiroth's purpose of enhancing his mystique. However if he were to use a super long Claymore instead, he probably would look less cool/scary, but there's a chance his techniques would be stronger. 


Now as for Sephi-Yog or Yog-phiroth-  The Masamune he wields is not the real Masamune. That blade is a piece of metal  that is insignificant to the eyes of an Outer God, even when he is fused with a mortal perspective.   The Black Key Masamune is in fact the Ultimate Key to the Ultimate Gate which Yog Sothoth is the personification of and simultaneously the guardian of.  He molds its appearance to LOOK like Masamune out of Sephiroth's nostalgia, however its properties are more that of a Longsword, from its weight to its balance.  It is a sword that behaves like an optimized weapon but looks like a ridiculous weapon so to speak.  How is that possible? He's Yog Sothoth, of course he can do that!

Parvarti sat quietly, overlooking the beachfront from the balcony of the hotel. Her face filled with worry as she hugged her knees. 

Silence bathed the room interior behind her.. the curtains waving slightly, almost just twitching from the wind that snuck through the open screen doors.

For a moment she just watched the sun set... and her eyes began to dim..

As her consciousness faded into sleep... a black feather drifted behind her  as a pair of golden eyes with keyholes  glowed behind her, set upon a silent smirking face..