Just to make things clear, does Sora, Ven, and Roxas each have their own keyblades? Roxas was able to dual-wield with his and Ven's, and Sora was able to dual-wield with his and Ven's, not Roxas', right? And did Xion ever have her own keyblade or was she using Sora's? I'm so lost right nowXD
Sora and Ventus for sure have their own Keyblades.
Ventus' heart is a chosen one which has the wielding ability inherently. Sora's heart did not have it at the start, but gained wielding abilities of its own due to connecting with Ven's heart.
Important point to note: Sora's heart
only gained the wielding
ability through Ven's heart. Him gaining the Keyblade in KH 1 from Riku was due to the strength of his own heart and he used the latent ability gained from Ven to wield it up to Hollow Bastion, where Riku took it from him because Sora's heart wavered and this Keyblade was originally meant for Riku. After getting Donald and Goofy back to his side though and regaining the Keyblade (which then choose him for good), Sora awakened his own personal wielding ability.
Although it is hinted right now in DDD that Roxas, like some others of the Org, has a heart, I won't dare to say he has an own Keyblade, he always used Sora's, and after he awakened it, Ven's for dual-wield.
Xion's Keyblade was a copy of Sora's with the same functions, but nonetheless a fake.
Okay, look at it this way... Ven had a keyblade first, Ven's keyblading ability helped Sora get HIS OWN keyblading abilities... So
- Ven has his own keyblade
- Sora has his own keyblade
Roxas only had the ability to use Sora's keyblade, as did Xion... When Xion "died" Roxas obtained the ability to use both Sora and Ven's keyblades... Neither Roxas nor Xion had legitimate keyblades of their own. Also, neither of them will be able to wield a keyblade if they don't have a heart of their own
Agreed, although Roxas' and Xion's state may possibly change in the future if the things revealed in DDD are to be trusted.
I'm sure it has more to do with some of them actually having hearts, (Roxas having Ven's | Xemnas possibly having someone's | etc)
Nope, that's not it.
Xemnas says: "We didn't stay without hearts."
and "Each indvidual was different, but some of us had hearts
being born inside of us."
Before that, Sora rants on Xigbar that he saw the memories and sadness of Roxas, Naminé and Xion, and how they were able to shed tears which is proof for a heart.