Lignum Vitae is now endangered - very hard to ethically acquired. It has a beautiful smell, and olive look - very hard and very heavy.
There is nothing like it. Requires no finish, withstands the worst impacts you can imagine. It was almost wiped out in the nineteenth century both because of the medicinal value of its resin (cough syrup -- guaifenesin -- was originally made from it) and they used it for self-lubricating thrust bearings to keep steam ship drive shafts in line -- and twenty of you together can't equal the torque hammer impact of a ship's drive shaft going to flank speed.
I had a pair of bokken milled from a stick I acquired in 1994 in San Diego. Never looked back.
They are now using a more plentiful subspecies or related species from Argentina and Venezuela, which has many of the same physical qualities of the Carribbean native tree, a largish shrub, really (another reason larger timber is hard to come by). I cannot recommend it more highly.