Um...I'm not certain most of that last post applies, Doc. I say left side because Cruallassar, preferring to shoot right handed, would turn his left side forward towards his target. His bow hand, head, and draw hand would form a direct line between him and the target, and since your attack is coming from that intended target, his arm would indeed shield his face. 
Furthermore, after my earlier post...the first time I tried to shoot these arrows, since I've done that in three posts now...you said that your tail, with the net to make your whip attack, was still snaking across the ground in [i]preparation[/i] for the attack, not actually making it. In fact, in your own words, "[i]At the same time its tail darted along the ground towards Crual, though judging by the distance it wouldn't reach its target in fast enough to get close before the arrows came.[/i]" There is too much time between you throwing the rock and my making the attack, unless you're trying to retcon your own posts, to strike in such a manner that you can disrupt my shot, made nearly instantaneously after appearing, which is as your thrown rock passes through the space of my head. Especially since doing so is basically akin to me making a counter post that says that Cruallassar is not so foolish a Ranger as to come within striking distance of you needlessly...which is true...and thus being far enough away to avoid your attack without even knowing it was there. 
Finally, with regard to the damage you believe should be done, it doesn't matter what kind of monster is at the other end of the rope/tail. The fact that there is a lot of muscle is the only relevant fact, and the absolute most damage I can see it doing is crushing a few ribs, and that is only if A: there is a substantial, massy, and solid enough block of rock on the other end to have such an effect, which I doubt, and B: assuming they are on a direct enough path straight towards my center of mass, otherwise they would glance off the sides of my body doing lesser damage, if not missing entirely. The entire target of that is about four inches across. Now, I assume that Shashous has a great enough control of his body to be able to accomplish B except that due to the imprecise nature of Cruallassar's ethereal shifting and the change made from the rock's appearance, it is entirely possible that his location could be displaced by four inches horizontally in either direction, throwing off any aim you make before he actually appears. In addition, since you did not specify A, which would require chunks of rock at least as big as a softball-probably bigger-then I make the most realistic assumption, which happens to be in my favor. Specifically, that since my net was in fact only glued to the rock and not embedded into it, that only shards and smaller chunks of rock that were attached to it would come away, and not the massive hunks of rock that you would find if you pulled out something embedded six inches into the solid rock. This leads to the conclusion that I reached in my post.