As I've said the Chief would win IMO, but your wrong on some points. Ya your right about the plasma sword barely working on him, exept for the fact that it can kill him in 1-2 hits?! The chief maybe a tatical genious but then again he's not exactly fighting a war here. But the basic jist of the fight would go as such, lets say they are fighting in Ivory tower. For the most part Gannon would float in the middle of the level maybe flying into one section or another to take some shots at Chief, maybe throw a magic punch or kick, in which the chief would take full on draining his shields and reatreat into a hallway or simply jump over turn around and blow Gannon a crater in his monsterous back w/ the shotty. Gannon would then probably try and pull some turn around slow low flying leg sweep, which the chief could just jump over again. Gannon would then go back to the middle and throw a few magic balls...That could end it there, but I doubt the chief would actually get hit, he'd proabably go get the sniper and then run around various corners shooting when Gannon loses track of him. Secondary weapon shotty. Done deal