Regarding the service, it’s the same as what I mentioned with the task earlier. You’d have to use the Owner actor to cast it to the Guard AI and then access the grapple component/data.
I’m guessing that he’s asking you to use Event Receive Tick AI in the service to get the grapple component through Controlled Pawn and then storing the information about whether the grapple is active or not in a Blackboard key.
As for the implementation, there’s not much I can give on that without knowing more details about the execution flow. If you can share a flow chart sort of setup showing all the logical steps involved in the the grapple mechanic, including what causes the AI to trigger it, and how the player can respond, whether it’s always a grapple or is it sometimes a melee attack and what determines the distinction, etc, then I might be able to provide a more clear answer