Tsujoi wrote...
Why doesn't Kirito use dual wielding all the time?
Well, in SAO its obvious that Kirito does not want to stand out too much. Having that unique skill really increased his fame exponentially, especially since he basically 1 maned a raid boss, and then dueled Heathcliff.
ALO has no dual wielding skill. He is using his own skill and memory to re-preform the moves (hard to do and makes a lot of mental stress). There are also no sword skills. So Kirito is manually inputting the combos essentially. They do not explain it fully until vol. 7, but the amount of speed and skill needed to just do an +8 hit combo means that really only a few players can even do things like this. Doing something like star-burst stream which is 16 hits, is considered impossible. He used vertical square, which is only 4 hits, to win. Vertical square is like I'm doing a hadouken and there is no input for it in the game.
Later in the novels, ALO introduces sword skills and the ability to make your own. Kirito can still only do a 12-14 hit combo (he only has to do it once), which is basically god like and only possible because he is using nerve gear (stronger than the AmuSphere) and he has so much exposure to fulldive tech.