Most games that have attack animations or a wind up for the attack usually have some form of a parry or counter move you can perform to reverse the attack and knock the enemy back (Reversals in kingdom hearts, Parrying in dark souls)
so my suggestion is, why not bring something similar here?
when the enemy reaches the peak of its attack charge (when the circle below it forms completely) if you hit it with its weakness at the right moment after it forms you can knock the enemy out of its attack and deal more damage to it
for example, when a wolver is done charging and its about to bite you hit it with a flourish and it will knock it back and take a bit more damage or when a retrode forms the laser line and sticks its head forward to shoot you hit it with a elemental shot an it will rear back and take more damage
-1. The concepts you have are great, but it could potentially lower our overall DPS because of the knockback, and it could provoke new players to be much less defensive, something that would come back to haunt them later on.
It's also a little biased towards players with a good connection. Players with a bad connection would just get hit by trying this simply because there'd be too much delay between the enemy attack cues and the player actually attacking.