A working bladed weapon made of wood. It could be a sword, a dagger, an axe, or evena throwing star, as long as the blade is made of wood.
Now such a thing might be feasible in Real Life
(in terms of slicing, not simple piercing), but in fiction, such things are often at worst only slightly less powerful than a metal weapon.
Yet sometimes these weapons can be shown to be greatly inferior, usually to show how outmatched one side is.
Some characters make deliberately make blades out of wood, as often a "calling card".
A Super Trope
to Wooden Katanas Are Even Better
(when such katanas match or best steel katanas
Compare Simple Staff
, Batter Up
, Wooden Stake
, Blade on a Stick