Grandia's battle system has it's good parts and bad parts, particularly that you level up your abilities by using them, something lost on so many games these days. I think, if you are leaning more toward the Action-RPG style that you'd want to provide some kind of actual movement control. The Grandia battle system provided no control over movement, the character would make a bee-line to the selected enemy to perform their Attack action except when other enemies/characters were in the way to impede them.

I think your idea is most like the Grandia battle system in that if your attack landed prior to the enemy's attack it had the potential to CANCEL their action completely or at least do some kind of bonus damage for the enemy being unprepared. I enjoyed Grandia's hybrid time-based battle system because of this as it usually worked more in your favor than the enemy's. Personally I prefer a turn-based battle system for my design but it will fit well into my scheme. Counter-attacks can be great but, like credit cards, are not accepted everywhere.

Another idea would be to seperate the action into reaction patterns and single actions.

Reaction patterns would be things like do I dodge or block the next atttack, Am i going berserk sacrificing my defense or do i fight defensively. Reaction patterns are always passive meaning either an reaction for an action of the enemy or the modify an action you are performing. Reaction patterns continue until you change them.

Single actions would have to be activated would be once performed with absolute priority and then you would continue with your normal reaction pattern. A flip would be a candidate for that or a single charged attack, whereby some actions would be caompatible with reaction patterns (meaning the would be modified by them.

So for example a charged attack might be performed more agressively when you activated the berserk pattern.