Even if it does require paying attention, it can still be misunderstood if you don't know how the nerve works and such. In a way, the way Mark put the attack looks like he made it so he could use it later in the fight, not in the same post. Now if he had said the spears would go when he stretched out his arm then it'd be clear that the spears were sent as an attack right then.
I'm not really torn on making the rule. I just feel a bit of common courtesy for those unfamiliar with the terms shouldn't have to be enforced with a rule. Just because you're a veteran RPer won't guarantee you'll know different terms be they medical or even military.