Narratively speaking, how is that any different from what the rogue does? They analyze your movement, and exploit your weakness with a devastating attack. They're just really good at it, and don't need a round or two to figure things out.
Sure, but by your logic, our suspension of disbelief ought to be strained to the breaking point by the fact that no matter which weak spot a 5th-level rogue finds and stabs, it always amounts to the same 3d6 damage. Surely some more vulnerable monsters ought to take more, and less vulnerable monsters ought to take less, right? Just as surely different monsters ought to fatigue at different rates. To keep the bookkeeping in this game sane, we abstract and generalize. And it works. For most players, anyway.
Eh, it's a matter of degree. Saying that something is equally effective on everything that it does work against requires less suspension of disbelief than just saying that it works equally well against everything regardless of what it is. Saying that it's a binary result, rather than a spectrum, is less extreme than saying that it's universally effective.
If you're going to justify a different mechanic, then it's mandatory that it reflect a different narrative, or else it causes issues with internal consistency of the world. You can't have one narrative that uses two different mechanics, or else the outcome will depend on your meta-game choice of which mechanic to use, rather than flowing from the in-game reality which the mechanics reflect.I'm not sure you need a different narrative, but I think of it as more actively engaging, assessing, and dissecting the opponent. What ever the narrative difference between advantage and normal attacks is I guess. I feel the tennis analogy was fairly solid (I think that was this thread)
I wouldn't say it's mandatory, but I will agree it's preferable. For instance, ideally I would like to see sneak attack and critical hits be more related than they are, since by my reading the rogue is simply landing such hits consistently. But that said, I have to agree with [MENTION=83242]dave2008[/MENTION] that he has provided a sufficiently distinct narrative for this martial "charge up" mechanic. Getting into a combat "flow" and gaining the upper hand on opponents not so attuned is very different than making sudden, unexpected strikes at vulnerable points.
