Sasori lost all of his abilities as an edo, and was nothing compared to his battle against Chiyo... oh and Sakura was there too. Anyways pre-death sasori is far more dangerous than kankuro could hope to be.
Agreed, but he still had his fearsome puppet mastery and intelligence, he could have attached his chakra strings in Kankuro's puppets and made them his own, he didn't even use himself, you know he himself is a human puppet that has many weapons, that's why I think he could've killed Kankuro if he was serious, he just got emotional from Kankuro's speech and his emotions cancelled the Edo Tensei for him.
I dunno why Kishi is trolling Sasori, in his fight against Chiyo and Sakura, Chiyo said that he had an opening, but he willingly accepted to die at the hands of his parents, it was his emotions that killed him.
And in the war his emotions kicks in again, he can't be THAT emotional! :T_T: