Purchasable Black Spear

Unsure if the purchasable black spear is in the shop mistakenly or if it's supposed to serve a purpose. I was lead to believe that purchasing and using it on a teammate that isn't already soulbound (after having already soulbound someone else) would cancel the initial soulbound and allow me to use on the new teammate. Whether this is true or not, I have no idea, but if that is its intent than it's not working currently. Appreciate a response on this.