Birth by Sleep Aqua,Kairi, and Riku?

The best systems should allow for the viewer to understand the complex systems purely by observation. An info-dump on how the system functions should not be necessary. However if they can't do that, then an info-dump is better than leaving the viewers to think that the author is doing whatever the hell they want.

 

Hm, well, in the end it is a matter of perfences. Some stuff can be just too random and not well thought out, but it would be nice for some things to be left open. The authors/gamer makers really have their work cut out for them when it comes to this. And plus there are some who go for it for money or are rushed by deadlines. And each person likes different things. So there are a lot of factors to this.​

 

Perhaps when Ven merged with Sora's heart, it's considered to be a kind of inheritance, not to mention Vanitas also wielded a keyblade and merged with Ven, so technically speaking, Ven could wield two keyblades.

Roxas used Sora's Keyblade for his fights and Xion used Ven's

Besides, I think Sora has to say the following words or when Sora becomes a Master, the keyblade might lift an restriction placed upon said state.