Ansem Sod's Body

[Sephiroth0812]

Actually, Vanitas not only Ven's darkness but also half of his heart ?

Exactly, maybe not exactly half (the broken off part we see in Ven's station isn't the half of it), but the heart of Vanitas was a part of Ven's heart before, yes.
One could say Vanitas's heart "evolved" out of a cut-off-part from Ventus's heart.
In essence MX created a heart out of another heart.

 

[Crystal]

Vanitas is Ventus dark half heart

Exactly, maybe not exactly half (the broken off part we see in Ven's station isn't the half of it), but the heart of Vanitas was a part of Ven's heart before, yes.
One could say Vanitas's heart "evolved" out of a cut-off-part from Ventus's heart.
In essence MX created a heart out of another heart.

Something i'm still confused, at the end of Final Vanitas' battle. Is the X-blade had been destroy causing Ven's heart injured or the elimination of Vanitas? >.>

 

[Sephiroth0812]

Something i'm still confused, at the end of Final Vanitas' battle. Is the X-blade had been destroy causing Ven's heart injured or the elimination of Vanitas? >.>

Both interpretations exist, yet counting in that the injury is several magnitudes more severe than last time the x-blade being the main reason is more plausible.
Furthermore, if Vanitas was destroyed for good so was his dark heart, which was once a part of Ven's. If that's the case Ven's heart would never be able to get the cutted out part back again and has to be healed otherwise (if that is possible).

As Vanitas said, both their hearts are connected to the x-blade, so destroying it would also destroy both their hearts.
The only reason Ven's heart wasn't destroyed completely is because the blade was incomplete.
Had the x-blade been fully complete and Ventus had destroyed it, his heart would have been completely vanquished.

 

[Crystal]

Both interpretations exist, yet counting in that the injury is several magnitudes more severe than last time the x-blade being the main reason is more plausible.
Furthermore, if Vanitas was destroyed for good so was his dark heart, which was once a part of Ven's. If that's the case Ven's heart would never be able to get the cutted out part back again and has to be healed otherwise (if that is possible).

As Vanitas said, both their hearts are connected to the x-blade, so destroying it would also destroy both their hearts.
The only reason Ven's heart wasn't destroyed completely is because the blade was incomplete.
Had the x-blade been fully complete and Ventus had destroyed it, his heart would have been completely vanquished.

So, it makes Ven's heart injured same as the time when his darkness being extract?
Then he goes to Sora for recovery.

 

[Sephiroth0812]

So, it makes Ven's heart injured same as the time when his darkness being extract?
Then he goes to Sora for recovery.

I don't get that part fully, but I'll try nonetheless.
Ventus's heart got injured two times, yes.
The first time was when MX extracted his heart to cut a part off and extract the darkness from within it, creating Vanitas in the process.
Vanitas took much of Ven's energy and started to gnaw away on his remaining heart, causing him to get critical.

This injury was mended/healed by Sora's newborn heart and formed the very close bond between both hearts.

The second injury came when the x-blade was destroyed. This injury was now far worse than the first one, because even the connection to Sora's heart couldn't help Ven's heart this time. The injury simply was too grave, to actually "survive" the heart had to find shelter inside Sora's, where it can rest and experience some relief from all the pain.
In the best case, this is maybe allowing for slowly recovery/recuperation, but we don't know that for sure yet.