Many years before my father died, and before I became as invested(infested? addicted? -- you choose) with Aikido, he impressed upon me the outstanding qualities of lignum vita. He had a rectangular block of the stuff that was milled from a old healed-over broken limb that was milled almost smooth on two faces, with rough bark, and naturally debarked surface on the other two sides. Very symbolic, that piece, and fascinating to me.
Lignum vita is a fascinating wood on many counts. It is a highly resinous (but not sticky), with a tight cross-grained figure that ranges somewhere from greenish gold to rich brown and is very dense. It is the source of guaiacum gum, which was the original source for guaifeneisin syrup (an expectorant). (It is my "medicine stick" in every sense.) It was also used as thrust-bearing blocks to maintain alignment of the propeller shafts of early steam ships because of its resistance to impact cracking, and because it was essentally self-lubricating when friction-heated. Tough stuff. Unfortunately it grows as a middling-large shrub, so large, clean pieces are hard to find.
The main objection to lignum vita is that it is hard to find and tricky if not properly seasoned before it is shaped . If not properly seasoned (1-2 years) it will tend to check rather badly. Being enamored of the wood,(which also has a faint but pleasing aroma) about ten years ago I had a wood worker in San Diego (almost Del Mar actually) take a 2x 2 in. dimensional piece of well-seasoned lignum I had worked to obtain (dipped in wax to seal both ends while it cured) and had two mated bokken milled from a jig he had made for a catalog production run of bokken.
Ten years on, and many whacks later, they show no signs of wear , no checks and no cracks . About two years ago one of my good kumitachi partners and I were practicing. We were doing kiai practice with good strong shomenuchi strikes received with a jodan gaeshi. When my turn came she pushed her jodan gaeshi a little too far toward uke nagashi, and my strike simply snapped her oak bokken in half about midway down the blade or close to the one third mark from the tip.
Not that I was trying, it was just in the way.