for that shield, a use limit, you use the shield and you are able to stop beams, explosions and like that, but your ki goings down, depending on the power of the blasts. i remember the shield atack on the Bif for power, in quake 3, that was a powerfull one.
as for the swoop thing i still keeping its good idea, i have another sugestion, i know its off topic here, but since i open this tread i dont mind ^^ (if i must open new one just tell me and i will do it)
i dont know if you have seen the film The Tree of Might. Turles use against goku a multiple scater beam attack (like kiblast attack but using a fast charged scater beams) besides, i have never seen goku or another one using it, just giving more ideas that give the game more strategies in fight