Grab? But you can block her 214B.
There are blockable grabs. Sion j.214A/C are grabs, so are all of Sion's whips, Sacchin 236A/C, and I believe Nanaya/Tohno AD are considered grabs, not sure about Tohno AAD, but I know Nanaya AAD is not a grab. A grab is just an attack that forces the opponent into a specific position regardless of where they were hit for the duration of the attack in game terms. They generally beat super armor in games because super armor makes it so you don't flinch, but if you're forced into a position it gets really buggy if the opponent is still able to move around during the grab.