The Eldar are quite fond of their webway travel. What scattered and barely readable records you have left indicate that mankind had been envious of such capability, to such an extent in fact, that the only reason why you could find this information is due to it being present in your own system. One of the reasons of your construction had been due to humanity’s endless drive and ambition of improvement. Only your masters could look at a webway network and think to themselves that they can do better. Unfortunately, it is not the time to espouse the greatness of your masters. The orks are coming.

In the mean time however, you must begin means of dealing with the Eldar. The first thing that had come to mind were specialized drones capable of detecting warp quakes, even the most minute ones, since the webway relies upon warp travel at least to a certain extent, it cannot be completely hidden. However, you know for a fact that you will need at the least tens of thousands, if not hundreds of thousands of such drones to locate the minute quakes that may or may not appear, you do not possess a truly deep comprehension of Eldar technology, so you will simply have to brute force your way through this.

As for other options, you had considered unleashing and endless swarm of nanomachines, but the needed quantity is vastly greater than the bots, and even those will take too long to produce, Eldar of this era seem to be particularly fond of flimsy, but agile style of fighting, preferring to deliver a punch before one can be given back to them. And you shall show them why your masters’ jaws evolved to take punches.

Then you still possess rather esoteric psyker technology that you still have no idea how it functions, even though you had clearly gone over its basic functions. Employing these weapons while not knowing their effects, especially against a race naturally gifted in psychic powers is just hoping for a disaster. Maybe it will cause the Eldar to spontaneously explode, or maybe it will super power them and allow them to commence “foul acts of sorcery”. As some of your imperial records would put it. As such, you will (despite your own curiosity) not be employing this equipment.

Lastly, you had the thought to refit the investigation drones with dedicated anti-sniping equipment, however, the reiterations you would need to undertake to modify the drones in such a way would take time, it would take time to refit or simply make new drones, yet again, you run into the issue of time, if you had time, you could do it. As such, rather than split your attention, it would be far more effective if you simply concentrate on a single solution.