I doubt the writer researched about guns.
In the first Sword Art Online, he did not research swords at all and it was all about swords.
Asuna has a Rapier. However, a Rapier is a blunt edge sword used exclusively for piercing. It is also useless outside 1-on-1 dueling.
Kirito also dual-wields using two long swords (one is a rapier and one is a sabre if I am not mistaken). Due to the size, dual-sword wielding is only possible either with a long sword and a short sword, or two medium-size swords.
If both are long swords, they are too big to actually wield. Also, the wielder should have really strong hand muscles or be ambidextrous. But usually, a sword's movement is a circular arch. The bigger the sword, the wider the circle. If they have two big swords, either the two paths intersect or hit the ground and either case is very dangerous. Moreover, it is technically difficult there are few records of it actually being used and no records of being used in battle.