How is the Rasengan not a Konoha jutsu? It was invented by the Fourth Hokage.

Orochimaru isn't so retarded as to not use high level jutsu when in danger. Sarutobi had already killed two Hokage and was about to kill Orochimaru. All Orochimaru could do was ineffectually stab Sarutobi with the Sword of Kusanagi. Orochimaru was lucky to leave just his arms in Konoha.

Orochimaru definitely went all out against Sarutobi. He freaking used Edo Tensei to try to resurrect three Hokage against Sarutobi.