Swords, I've always been fond of them. A beautiful sword is literally the first thing I searched for in this wonderous game.
When I stumbled upon a Long Sword (such beauty I might add), I thought: "Well, this must be the longest sword in the game, right?"
The question has left me wondering ever since.
Which sword is the longest?
Although length is not as important as the sword's overall design (and there is an abundance of well-designed weapons, long or short), I finally did some research, and compared some of the swords I had. I'm sure there are quite a few missing, yet I hope that I've captured at least the few swords that rivals the Long Sword in length.
Now let's feast our eyes on some beautiful swords! The following pictures were captured in the same pose (it's a one-take, with absolutely no character movement) while under the effect of a Ghostly Hero tonic. Therefore the sizes of the swords in these pictures are comparable. The swords are arranged according to the horizontal length from the handle to the tip. Some swords may seem larger due to the curve, or the longer "tails" (the design at the rear of the handle). It took a while comparing them one-on-one, and some of them are really close in terms of length.
(The enormous ones)
(The medium ones)
(The medium-short and cute ones)
The names of the swords, from long to short
(The enormous ones)
Wyvern Blade
Sephis Sword (a needle-like tip makes it slightly longer)
Obsidian Edge (surprise! it's almost exactly as long as the Emerald Blade)
Emerald Blade
Dead Sword (also a surprise for me)
Long Sword
Turai's Sword (I'm amazed it didn't make the top 5)
Runic Blade
Greater Sage Blade
Fellblade
Wingblade Sword
Colossal Scimitar
(The medium ones)
Fiery Dragon Sword (flames not included)
Gothic Sword
Platinum Broadsword
Crystalline Sword (actually, it's a quest reward from pre-searing)
Brute Sword
Jade Sword
Forked Sword
Plagueborn Sword
Oni Blade
Shadow Blade
Fiery Embersteel Blade
(The medium-short and cute ones)
Emerald Edge
Elemental Sword
Sage Blade
Katana
Shinobi Blade
Broadsword
Vertebreaker
Lesser Sage Blade
Dadao Sword
Fiery Gladius
Jitte
Golden Phoenix Blade (has a long and beautiful tail)
Short Sword (collector folks like to call these "Long Swords")
So there you have it folks! What do you think? Is the Wyvern Blade the longest of them all? Did I accidentally miss a few very long swords?
As a little bonus, I went to test the length of Turai's Sword compared to the Eternal Blade (standing on the same spot as a Ghostly Hero NPC). Here it is:
And that's all for now. Thanks for reading. I hoped that I at least entertained you. 
