Board Thread:Questions and Answers/@comment-25908228-20141222101442/@comment-1173941-20141222103710

Asuna and Kirito are pretty close in strength, to the point that each of them is always saying that the other is stronger. Kirito happens to have a few more tricks that can throw people off guard, but in combat ability it's never made clear which is stronger.

Zekken chose Asuna over Kirito, simply because Kirito had noticed that she was a "resident of the world," and she didn't want to be around him for too much longer.

When it came to the fight with Death Gun and Kirito, you really can't say it had to do with weapon quality: After all, Kirito only landed one hit, and that insta-killed XaXa. You can either say that it's because Kirito got rusty, XaXa got stronger, or from the beginning XaXa was already stronger, and Kirito only beat him in SAO because of the massive level difference. It could be either of those 3 options.