If I was working with dreadknights I would magnetize all the weapon choices. So even if I had two knights (which I've seen most GK players do) I'd have both their swords already painted and just used as a weapon swap out. And from what I could guess, each kit only comes with one sword.
Other then that I'm not sure what people would do with the bit.
You should ask around in the GK main page, better chances of finding someone with it there.
Also always check with people at your local GW store, sometimes the workers will have lots of bits on hand, and sometimes they trade or sell.