system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why don't more Jedi use two lightsabers?

I understand that in human history warriors wouldn't conventionally use two swords because they took more than they gave, but lightsabers are much lighter than swords, and Jedi can use the force to still be dexterous. Every time I've seen a Jedi get their hands on a spare they've seemed more powerful for the fight they use it in and they neither seem any less adept or weaker because of only using one arm per lightsaber.
gpt
It's mostly a question of tradition. Jedi are meant to be peacekeepers, and their lightsabers are for self defense when diplomacy fails. Carrying an extra blade, or a double saber was considered to be more offensive than defensive. It wasn't prohibited, it just wasn't very common. 

More sabers aren't always more effective either, just look at Obi-Wan's fight against Grievous. Kenobi used defensive mastery and single precision strikes to overpower the General's onslaught. Dooku uses the same philosophy to disarm Anakin when he tried to fight with a second saber.

When it only takes a single strike from your weapon to win a duel it's usually better to defend and look for an opening than to try and rain attacks on your opponent. It's an elegant weapon, for a more civilized time.