Some cursed fraud of enemy hath beguiled thee. 9:905

Here Adam is talking to Eve and referring to Satan.  He says some enemy (Satan) has tricked her into eating to fruit.  Milton probabally wants to take some of the blame off of Eve, and put it on Satan.  Adam does not want to admit that eating the fruit was totally her fault.  In this line, he is able to shift some blame. 

Brooks Winchell