So for harvesting Demon Blood, I’ve found the best tool is the cleaver. From the Dragon south of the Mitra trainer, I got 5 blood with a hardened steel skinning knife versus 10 with a hardened steel cleaver. Blood is guaranteed off the Dragon so farm away. 20 Dragons should be (more or less) a World Map.
As an addition to the information pieceofgosa posted, there are a a number of elite spawns along the north side of the main river. They also drop demon blood.
I have always used a pick, though, and will certainly try the cleaver, thanks !
The snake is also my preferred source (believe you get 60 or so on vanilla rates) but I use a pick instead. Early on the blue eyed shalebacks were pretty good.