Sheesh these are better then my old Sarnak boots. 65th cleric and I am looking at these as an upgrade. Time to head to Nurga :). Too bad the old cleric ether mist boots from Hate where not anywhere near this nice....
I have killed the blood thirsty rat at least three times now in the mines and it drops the boots every single time, along with some blood thirsty rat meat. The rat also seems to spawn in the same place but it has a PH. It spawns in the room that used to have Overseer Dulbish. Just keep the room cleared.
Here is a map showing you where he spawns (look for #3): http://www.eqatlas.com/kunark/nurga1map.html