From an outsider's point of view, it might seem excessive of Sango to invoke the two strongest skills in his arsenal just to deal with some of God's apostles who are not even Gods and are supposedly not on his level.
This is not about their level or who they are representing. This is Sango's way of reciprocating the favour they had done for him by helping him to awaken his primal player instincts.
Going at them as a player with everything staked on the line. It is up to them to prove to him that they deserve to witness the miracles that can be brought about by using his eyes of despair.
The goal for them is not if they will survive or successfully vanquish Sango.
No, no, no. That is way far from the reality Sango has in store for them. With his eyes of despair awakened, and his grimoire by his side, the three duos only have the luxury of choosing one goal, and it is not optional.