As Roxas is a part of Sora, he also can use two.

Sora can wield two keyblades at once because he has Ventus’ as well as his own. Nomura also confirmed that Roxas was using Sora's and Ven's Keyblades to dual wield.Ī: Because he can use both Sora’s and Ventus’ keyblades. The cover art featured Utada Hikaru with two Keyblades, which Nomura said 'The fact that she has two Keyblade means she must have two hearts' Nomura confirmed that two hearts are needed to dual wield when he tweeted about drawing the cover art for OP and ED for Face My Fears.

In order to wield two Keyblades, one must have two hearts. that last one is a little silly since that means it's a replica OF a replica blade but whatever replicas are basically the same as the real things. Xehanort had 12 replicas of the organization ready to unleash on Sora he used in scala and you see a replica version of Vanitas's keyblade, Terranort's keyblade, Young Xehanort's keyblade, and Xion's keyblade. These two aren't the only one with replica keyblades the game has a whopping 7 replica keyblades in it. Xion is very much the same as Roxas she uses a perfected replica, the data and experiments they performed in the various worlds to fill in the blanks (though the exact how isn't known), and then past Xion's heart and later present Xion's heart. Roxas coming back as a completed person missing nothing not even his keyblades is the result of what Vexen's perfected Replica program was capable of. R oxas's body is one of his perfected replicas and Ienzo using the data on Roxas recreated a near perfect copy of his heart inside of it, making it look, sound like Roxas, and have his powers all it needed was the actual heart of Roxas to be completed which it got in the KG.

These two were prototyped/incomplete replicas and Vexen stated his perfected ones wouldn't simply replicate they would be capable of replacing making them identical to the real being/a human in every way. Xion did so in Days just by being near Roxas for a few days (Sora's memories getting inside of her was an unintended accident she was just supposed to replicate a few memory fragments not absorb the actual things) and then Repliku replicated all of Riku's powers in CoM right down to his soul eater weapon in CoM using Riku's data Vexen inputted. In KH3 the keyblades are replicas, this games have explained and shown before that the replicas can create replica weapons/keyblade of the person whose powers they are replicating it. Roxas's second keyblade is canonically Ven's but it was awakened by his experiences with Xion.

Roxas kh3