This simple dagger is surprisingly light and nimble. A small opening in the blade can fit and grip a rope of any size, and the blade itself can cut them in a flash.
You have a +1 bonus to attack and damage rolls made with this magic dagger.
Rope cutter. The corsair's blade can easily cut through any non-magical rope as if it was paper.
Rope swinging. The wielder of the corsair's dagger can use the small opening in the blade to attach to a rope and help them traverse it. The dagger's magic makes it so that, unless the rope is cut, the user can hang from the rope indefinitely using just one hand.
If you are a Patron you can get additional versions of this item: poker cards sized images, and for Foundry Tabletop in a separate post.