Pale Wooden Sword

Moonlit dool-wood that lets you cut what should not be cut.

Carved from a dool tree with a silver knife, then polished with oils infused with moonlight until the grain glows pale.

When you wield it against a manifest undead spirit, it can hurt the spirit normally. Reduce that manifest form to 0 HP and it dissipates — but the spirit can reform at its tether.