Sapient pearwood is a species of trees growing in intensely magic-polluted areas (usually polluted by spells cast during the Mage Wars). This tree or an item made of sapient pearwood is totally impervious to magic, and it seems also impervious to the usual knives, cutlasses, etc. Sapient pearwood makes excellent wizards' staffs. Still more useful is the fact that an article made from sapient pearwood will follow its owner everywhere, absolutely everywhere, across the space-time continuum, across all dimensions, if need be. For this reason, sapient pearwood is also often used to make grave goods, things buried with rich people or royalty so that they might be able to enjoy life after death.
Nowadays, these trees are rare except on the Counterweight continent. Sapient pearwood is extremely expensive around the Circle Sea, and even if a wizard has the money, there are no new sapient pearwood staffs available for purchase. On the Counterweight Continent, however, sapient pearwood is common enough to be made into luggage.