Alright, after watching a bunch of videos I think I have an idea of what to use for down Smash.... yeah, Jecht shot is forward air, the animation is exactly like the one in dissidia
Sometimes i feel like the characters in Dissidia dont have enough moves to make a PSA out of, i guess you're gonna improvise on some moves then lol. You could probably take some ideas from FFX, im sure you did with the Spell Cast B move. Not that he does much there though. I got some ideas for taunts if you're considering those yet lol:
1. Toss up sword and catches it (FFX victory animation)
2. Rears back and laughs (from that awkward laughing scene in FFX at Luca with Yuna) this one is a maybe lol, but if you want it use it lol.
3. Stands up straight and scratches the back of his head (like he does in some scenes if FFX)
4. Twirls blitzball on 1 finger, like a basketball
I will leave it up to you to decide which directions these could be assigned to, i have no clue lol