late reply but to me it means "people in the world of Bloodborne that have chaged into animals." If it says darkbeast Paarl for example, it is a beast. I would guess this excludes aliens, ghosts, people, insects even. I used the blood gem in quesion I think for quite a while, before the enemies changed to things besides BSB and Amelia etc. I dont think I got until after these obvious opposrtuities though.
I agree, granted there are a lot of achilles heel tricks to use in Bloodborne, but the base difficulty is as high as ever and people are not doing as well at SL4 runs as we did with the other games.