Why do people say that he needed the Bijuu's chakra for Indra's arrow? He used the Bijuu's chakra because he himself was out or nearly out of chakra. (And wanted to kill Naruto) if he had full reserves or probably half he would still be able to make it probably not on par but still able to do it.
OT Susano'o/PS have 4 arm's so probably 2.