Ideally, grudge should punish the player for not paying enough attention and failing to clear it off the enemy with a weaker move, such as the basic attack. But currently it lasts for two received hits rather than just one, often leading to a lot of time having to be wasted to clear it off an enemy. Even the grudge trap applies it for only one turn, to my knowledge.
So I propose the duration of grudge’s effect be reduced to 1 turn–applying only if the next attack against the user knocks it out.