Defensive feints applying to an entire turn's worth of attacks, rather than 1 attack, per Kromm in 2008: http://forums.sjgames.com/showthread.php?t=36363 "they apply to every attack that foe tries against you next turn. The rules use the term "attack roll," singular, simply because the combat system doesn't assume multiple attacks in general."
can be done during a Dual Weapon Attack, per PK in 2010 http://forums.sjgames.com/showthread.php?t=68694 with 2 options "Feint as part of your DWA offers you the chance to trade a small defense penalty for a larger one, no change, or no penalty at all, depending on your relative skill and luck."
the 2nd half of the DWA benefits from the feint (sequenced) INSTEAD of the -1 to defend against DWAs, since it is no longer technically a DWA
the 2nd half only benefits from the guaranteed -1 (simultaneity) and not from the feint, which only applies to the next maneuver