Is this character specific?
I think you’re referring to ex fba’s claw attack’s one hit-ex.st combo? No, it’s not character special.
Yea I was, Thank you for replying. I shouldn’t have made a thread for this, I apologize.
Anyhow, any sort of trick to landing this? Can only seem to get it about 1/10 tries
Some characters are harder to do on then others. Hardest character to do it on is cammy. If you can practice on her, you can do it on anybody. Just make sure to get the st to come out as soon as possible. After the db, f motion, I double tap the kicks so I have more chance for the special to come out. Or plink it. You should be charging for the st just before you slash after the ex fba class. Needs to be single hit, so make sure to not leave the stick on neutral when doing the slash. The slash should make contact on the edges of the claw
After the ex.fba in the corner (assuming for now the opponent is in the left corner), press right, and so be on the right of the falling victim. There, when you are closer to the ground, press down-back+punch and one slash will come out as vega will try to izuna grab but must be out of range for it. Do not let the down-back charge go. And as soon as you recover from fba on the ground, do the ex.st motion.
doesn’t need to be close to the ground, can be pretty lenient in height.
Is there any benefit to spending the meter on it vs just using Izuna drop?
I just maneuver myself so that the opponent is in the corner, then on the way down pretty low I press punch. Only one hit will come out. You can start charging the ex. st when you land basically there is enough time. It can hit lower than you think. I find that the trick is making sure the claw slash hits when Vega is falling.
I know there is an actual reason I read somewhere, but for me its purely a style thing. Think it was something like more damage or stun at the cost of 1 bar and sacrificing the hard kd
It does more damage and stun at the expense of the hard knockdown. Plus it looks stylish 
jumpin -> cl.hp -> ex roll -> cr.mp -> ex fba -> ex st was the most damaging combo Vega had pre-ultra. There’s probably a more damaging one involving RFC now.
I mostly only use it if I know i will stun someone. Plus I have meaty setup after the soft knockdown
With all the scaling it’s a waste to use up that much meter and your Ultra though. I’ve noticed that scaling causes the damage output to be no better than a well timed Ultra. Sometimes you only get a little more damage than a shorter combo using less meter as well. I’d rather keep the meter I suppose.
Vegas j.hp beats out alot of normal anti-airs that people are used to working, so it happens that you can land that combo without scaling. It does like 426 or something for three bars. Pretty good if you ask me. Most of the time it is better going for the izuna drop at the end though, for positioning.