Waltwood
ウォルトの木材 [walt no mokuzai] or 'walt lumber' in Japanese. The name may imply that the tree is similar to walnut trees.
Grimoire of the Rift

Buy: - (sell: 65 gil)
Use: Barong, Cleansing Staff, Healing Staff, Iron Pole, Judicer's Staff, Mage Manual
Reward: Kids These Days x3 (once), Foodstuffs: Aroma x3 (once)
Type: Timber, Rank: —
Description: This cut raw waltwood lumber is naturally impregnated with tar, making it highly resistant to water damage.
Final Fantasy Tactics S

Buy: - (sell: 50 gil)
Use: Bow
Obtain: Rhode Rum Region/Great Forest of Madol
Description: A somewhat uncommon timber
Category: Item