Brenda's fascination with the Masamune katana

The thing about the Japanese is they are renowned for not giving away any of their culture. Martial Arts for example. Even now, people are only just finding out true meanings of techniques and Kata, despite Karate being taught to outsiders since the end of World War 2.
So the existence of the sword, for me anyway, is a nod towards this habit the Japanese have of keeping things to themselves.

RussellNash... I very much like your theory, and I'd say it mirrors my thoughts to about 95%!

The only difference I really have is that I like to think the sword making in ancient Japan was exactly where we think it should have been. Masamune was just one of those once in a generation genius craftsmen that so far exceeded anyone else around him that it took generations for everyone else to catch up. I would say he is the sword making equivalent of Albert Einstein; someone who was able to look at the way things were, but could figure out the way things should be.

The difference between Masamune and Einstein was just the era they live in. Master sword makers (even in reality) were VERY protective of their secrets and methods. I could imagine that Masamune transformed the way that swords were made, but kept his methods completely to himself. That probably explains why his name echos down through the centuries... so distinctive and unique were his methods that a Masamune sword can be distinguished from another sword from the same era. And then, in one brilliant stroke of genius, he created that Magnum Opus, which was an epic achievement, even among his other achievements. These secrets he never passed down, and so the legend of the Masamune sword was born.

Einstein, by comparison, lived in an age when mass communications existed. His ideas were openly shared and spread around the world. Where Masamune kept his discoveries to himself, Einstein was peer reviewed and broadcast world-wide.

I like thinking this way simply because it keeps Masamune very human, albeit a transcending intellect for his time. It keeps the Immortals special, and unifies a literal immortal (Connor) with someone who's legacy is immortal (Masamune), and shows that, even though he is immortal, Connor still holds the legacy of humanity in his hands. (And it keeps out the awful alien stuff from the second movie!)

I had also never thought of your other excellent point that it will help a sword, even a one-of-a-kind sword like Masamune's, survive the ravages of the centuries if a single owner is constantly caring for it. I imagine most of Masamune's other swords were lost to time, fell into disrepair, or were destroyed or melted down by others over the tumultuous history of mankind.

Cool stuff to think about... thank you!

Interesting ideas. For me, I thought that if it wasn't merely just a plot device to explain Brenda's deep interest in the sword beyond being a murder weapon, I figured maybe it was because since immortals lived so long, that Ramirez picked up many bits of swordmaking knowledge over the years that were lost to history or were from such different cultures in time and location that they never would have come together and he passed them on to the highly skilled Masamune, who was able to harness that knowledge to make such an awesome sword.