First and most important is QUALITY. In how it is made and the artistic expression. This translates, to me, as "soul." Lovingly hand crafted.
This is why I collect HI as the one few exceptions to antiques. Simply put, HI products have soul.
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I have heard that long ago, quenching to temper a blade came from using a red hot sword for execution. They found that after a red hot blade was thrust into someone to be executed, the blade would hold an edge much better. It was thought that the soul of the executed then inhabited the blade.
If you look carefully at the hilt of a Dayak Mandau, you will see, among the decorations carved there, something that looks like apostrophes. These are representations of leeches. This was supposed to give the sword a taste for blood.
The handle, scabbard and blade were often made by different people in careful concert with each other so that when brought together, there would be no jealousy between each spirit and another since each part was considered to have a spirit. Then a cermony to bring these separate spirits into one.
I'd bet they have a similar ceremony in Bir Ghorka.
In many societies their sword was by far, their most important and most valuable possession. Often cherished and handed down intergenerationally.
One of my favorites is a Chinese "Willow-Leaf" Dao )Yanmadao). Early Qing dynasty. It has a very old repair to the blade of about thirty tiny rectangles of metal that were welded into the blade. Each rectangle is about half the size of a drain of rice. You can not feel them and can only see them in a very good light.
Don't know why the repair was done. Perhaps it was pit holes. As you know a good steel blade can suffer quickly if exposed to moisture. This was Phil Tom's suggestion.
The repair had to have cost much more than the sword was worth. This tells me that the sword had an intrinsic value that far went beyond market value. Somebody really loved it for what it meant to them -- family heirloom?
The balance is exquisite. But it has a presence, at least to me, that shows centuries of love and respect. A trail that has led to me and will continue, hopefully, long after I am gone.
While answering this, I thought about what is my favorite edged piece? I could not choose one. Each has it's own qualities, but they all seem to center on the blade more than handles or scabbards. Whether it is a Khuk, a keris, a headhunter's mandau, an old Roman or Chinese sword.
The soul is in the blade, so to reaffirm my original answer, my collection must have soul. And, I feel, that we, as temporary custodians, MUST RESPECT that Soul, else WE are unworthy.
I am going to get out some incense and some scented oil and have a little sword and knife party. Ever smoke one of your blades? I think they (he) will like that!
Mine do.