There are a lot of reasons why you should utilize two-handed weapons. But the most obvious one is for more damage output. Although the damage boost is not that big, every hit will count in those important boss fights.
Dual-wielding or two-handed weapons may take some time to get used to. Since you focus more on attacking and you don’t have a shield, you need to be more agile and adept at rolling or dodging enemy hits. This can be quite challenging especially if the enemy has a different windup speed than usual.
Another pro is it gives you access to new movesets. These moves allow you to utilize a weapon to its full potential damage and unleash devastating powerful attacks on your foes. Like any other weapon or ability, two-handed weapons come with their own boons and banes, but learning how to use it will definitely make you a better player in Elden Ring.