A Yew shieldbow (u) is cut from yew logs at 70 Fletching, granting 75 experience. An unstrung yew shieldbow can be strung using a bowstring at 70 Fletching, granting an additional 75 experience thus making a yew shieldbow.
With the release of Invention, unstrung maple, yew, and magic shieldbows gave more experience than intended when disassembled. As a result of this bug, the street price of unstrung bows were going for over 3,000 coins each.