One more thign, woudln't the battle at fort Xiang Yang prove that Yang Guo's internal energy is better than the GWM's.
Ranking hte weapons used: 1) Goldwn Wheels 2) normal sword used by Yang Guo, 3) Wodden Sword used by Yang Guo.
Since 2) and 1) countered each other, the sword broke but so did some of the wheels. Doesn't it mean that Yang Guo's energy must be highte rto use an inferior weapon to break the wheels?