In actual reality people are quite bad at coordinating similar weapons and don’t get much benefit out of it.

so this is what led me to really think on this one: if people are inherently bad going at it with two of the same, a specialization / class benefit / perk whatev that made each weapon equally effective would incentivize that pursuit.

know it's very much fantasy. rapier and buckler / parrying dagger / daisho - these let you use your dominant arm for the larger weapon and play defensively (esp buckler) - same with a knight wielding a shield and sword - to my goofy logic this wouldn't require a special skill or perk, hence wouldn't be dual wielded.

but, as stated in other replies, I'm also probably mixing up rpg systems like palladium's rules too, because most of my playtime was a few decades ago lol, and tho I played AD&D and 2.5, I payed a lot more tmnt.