What's the point of the shield if a grab can bypass it?
Seen way too many 1v1s were one person just grabs the other and insta win since instant death gives them guaranteed heavy hits.
The attack move sets are designed after Rock, Paper, Scissors. Each move has a weakness to another. Attack wins over Grab. Grab wins over Block. Block wins over Attack. If another player constantly uses the same move over and over, then this knowledge can be used to your advantage.