By the way ... NO ONE fight in messy and real battle without shield if you don't want to died. Even more true if other have arrow, and you don't have plate armor.
It's just suicide.
And all the cool but idiotic thing from game and movie with dual-wielding weapon are mostly lies, crapy and silly mean to kill yourself.
By the way, you can't cute a chain-mail with a sword. You can't also break a iron or steal armore-plate with sword : you need axe to do it or a blunt one to break the bones inside. Same way, hield are great weapon themself, can be used to cancel your next move with your weapon, or hinder the see of the foe and many more. Shield are life, in a fight. Only one-against-one can you go chunibiu and play without it. Not in a battle.
Ok ... this strange power are clearly the goal of the Xis, and they clearly don't do that to help humankind and because they are good people.
I pretty certain now after some time, the MC will start to kill some Xis. But well, we will see !
Ombrelongue