Siva's power level is apparently over 9000, even though normal technology (read as non-paracausal) cannot reach that power level. When the Vex (obviously much more capable than the Fallen, in pretty much every regard) tried to fight Oryx with Quria Blade Transform, they got annihilated, because paracausality doesn't follow any "known logic", it has its own. (Books of Sorrows). One part of that logic seems to be killing and sword logic. Through killing Oryx, we seized his power. We are now undisputedly the mightiest guardian around, since no one has ever fought anything stronger. We are actually the strongest entity around in our entire galaxy, if we ignore a functioning Traveller and the Queen of the Reef. In terms of progression it makes sense that our first raid sent us to the Vex (since Oryx easily defeated them. So we have to easily defeat them as well, if we want to even start to challenge Oryx). Then we had to slay Crota, a mini Oryx. Stronger than the Vex, yet weaker than Oryx. The came King's Fall, and we dethroned Oryx as the mightiest being in the Galaxy (ignoring a functioning traveller). This is pretty much a perfect continuum and makes sense. Let's enter the present era however: we suddenly face off against some devil Splicers and their Siva creations, but they are much weaker than anything we faced before. How does this make any kind of sense? Why do we have to Raid against an enemy that is obviously weaker than our very first one (Atheon)? In that regard, the Wretched Eye strike is also horrendously bad. The devil splicers were able to control an Ogre, even though "not even Oryx can control an Ogre, unless he is taken". Now, someone might point out that this clearly shows how powerful those Splicers are. Which would bring me back to Quria Blade Transform. That fight established the general rule that paracausality will always win over causal technology. Compared to the space time shenanigans of the Vex, Siva is as causal as it gets. It should be impossible for Siva to be on the current power level and it makes no sense that an entire Raid is dedicated to this.