Board Thread:Theories and Speculation/@comment-25576506-20150406220206/@comment-4271790-20150408020815

"Power" can mean anything. In fact, the word itself in that context is vague. "Power" could mean ninshū, in this case. Hagoromo entrusted ninshū to Asura. Indra became jealous and developed ninjutsu. Thus, the brothers with their respective powers fought each other, ninshū vs ninjutsu.