Board Thread:Episode Discussion/@comment-24573226-20171012080158/@comment-34633327-20171015080450

For all we know it could be a Scorpion homage, just from a gauntlet and with multiple darts. Or it could be like the Slash Harkens from Code Geass, just human sized and not rocket propelled. Or it could be like Kirupika's chains (I don't know much about Hunter Hunter but I do know he can create chains that come off his fingers thanks to his Nen) and Watts has multiple darts for each hand.

The blade may not even be metal. Maybe it's made from the same material Grimm Masks are made from. Maybe it's a polymer he created himself. Maybe it's plain old bone? Probably not the last one.