Bronzewood

Bronzewood trees can grow 40 feet in height, although they take many decades to mature. Their branches grow from the trunk at 45 degree angles. The leaves of the bronzewood are narrow and toothed, about eight to ten inches in length; the bark is reddish-brown and very hard. The wood is very difficult to work with, but it can be used by experts to create weapons as strong as metal, but as light as wood.
Bronzewood is often used to make the most secure portals and doors. Especially in Dyvers, woodcarvers and joiners craft such with merlons and grooves so each board is dovetailed intricately to the next, making them much stronger. They're often bound in cold wrought iron and backed with a bronzewood crossbeam.
Saint Cuthbert's cudgel is said to be made from bronzewood.