Unlike Zoro's swords, I don't think that Brook sword is that special or legendary or any-thing.
What makes Brooks sword technics stand out is not the sword, but rather Brook himself. He is the one able to move so fast that you don't even notice he is cutting you.
He is the one able to call ford the coldness of the underworld and wrap it around the blade.. so well, I guess it's really not all that important where he got the blade from.
I do love a good cane blade though, I always adored the idea of canes with hidden swords.
Which is not a unique thing to Brook for those whom don't know, it was a real life thing used by aristocrats as they went to parties back in the 17'th century.
The Scarlet Pimpernel is also a fictional character, waaaay older than Brook, whom mainly used that kind of a sword. And were also able to fight with just the cane, but then pulled out the sword from it when things go serious.
It's a really really neat little thing to have, I love it. And I love Brook has one!