Is it because it takes his power from the owner will and in that moment obito was insecure or it was beacause of the attack combien of naruto and sasuke?
from the owner feelings to be more exact... u said more or less .. it was obito's condition , not Naru/sasu attack ,, if obito would be in his best condition Naru/sasu attack would be useless
I think it was like you said (the first one), at the time Obito was pretty insecure. In fact just before they made contact I think he had some flashbacks of him being the hokage.