Originally Posted by
Shuke
To elaborate more on the spoke "spinning freely" I mean that it's not connected to the hub and the nipple isn't connected to the rim. The spoke and nipple are however solidly connected to each other though. Trying to true that spoke would have no effect on the rest of the wheel because it is not connected to the wheel anywhere.
At the hub and rim, the spoke and nipple sit in their places respectively but there is nothing keeping either of them in place other than the drilled holes.
By "not connected" I assume you mean "not anchored". J-bend spokes have an anti-rotation feature built in by design. The j-bend going through the spoke hole keeps the spoke from turning. Straight pull spokes have no such bend and must use other means to keep the spoke from turning, either through a square shaped section like my Mavic spokes or use of a tool during tensioning.
Either your spokes always required a tool or that single spoke now requires a tool due to damage to the hub. Regardless, if you can keep the spoke from turning, you'll be able to turn the nipple independently from the spoke and apply tension to the spoke.