It's something we totally can buy with Legolas, the guy is a purely individual fighter who, in his homeland, is jumping from branch to branch to branch. He could pull out one of his swords with his right hand, whilst holding onto a branch, swing it, put it back, swing to another branch and perform the same motion in opposite because he's a thousand year old elf to whom individual fighting is not just second nature, its probably a form of instinctive magic to him.
There's a reason that later on the Mirkwood army and royal guards are shown in heavy armor with tower shields and polearms/longswords. Because those are the guys who will stand on the floor, in a block, and receive the foe. They aren't going to be fighting as individuals, picking their foes, so they're armed like sensible group fighters.
For the same reason, the dual wielding thing is just not going to get the same traction in our history. You don't have people that dextrous, with that much time, who are also individuals picking their own targets on their home ground.
It's just not feasible for war.