A much better version compared to BX. Not saying that the BX ver. is bad but how do I put it emmm...BX does not demonstrate Setsuna's combat style. The V version on the other hand is an improvement of the Z3 version and fits Setsuna's original battle style well.
The MAP and last attack for the 00 Qan[T], in which it goes Trans-Am and blasts that massive beam. With the 00 Raiser, it was called "Trans-Am Raiser" or "Raiser Sword". With the Quanta, it's popularly referred to as the "Quantum Sword".
Officially, that attack has no name. Only recently the games featuring the 00 Qan[T] have been referring to it as "Trans-Am Raiser Sword" or "Trans-Am GN Buster Rifle V". The term "Quantum Sword" was created and given by fans to separate it from the 00 Raiser's signature attack.
So when are we going to get an actual combat machine like seven saber? QanT was never meant to be a killing machine like his compatriats, it was meant to fuel Setsuna's crappy narrative. Sick of seeing the SRW team try to make it something it isn't...when there's a better alternative to work on.
Gundam 00 is probably my favorite Gundam show but for some reason I didn't like S2 too much. Te units design feels poor IMO (I loved S1 ones) the only units I would save are Susanoo and Reborns (which I think is awesome). One the other hand while I like Setsuna a lot the fact that he takes all the spotlight while the other meisters almost do nothing hurts me. It has its cool moments too like all the character development, the Trans-Am Burst and the final battles but even with that I still prefer the S1. It would be great (again IMO) if some SRT featured 00S1, 00F and FMP! together.
If you're talking about the Qant FS,there is the copyright issue. This was merely a speculation but it is confirmed after we saw the titles included in SRW X.