or none of thatSo either it's sealed up, Sasuke damaged it, or it's in memory of Neji or something.(part 1 Neji had that on his arm/leg)
He has a Zetsu clone arm. It would really amp up the Obito parallel.It could be a synthetic arm in which he lost the original during this current fight or he hit sasuke with a rasengan and broke every bone in that arm, or just to cover up the seal :| either way, he looks badass