Spoke Catcher ??? What's it for ?

It looks like it's a tool to hold straight-pull bladed spokes in place while you true a wheel.

Because straight pull spokes don' t have an elbow, as you tighten the nipples, what tends to happen is the whole spoke twists (so you don't get anywhere). WIth that, you can hold it still.

Never seen it called a 'spoke catcher' before, though.