I think poise is your ability to take a hit and still keep your balance, could be wrong, but that seems to be what is happening. Darkroot is just there down the stairs from the Blacksmith near the church if you don't want to see the fat guy with the club, to defeat: - . Buy the crest (20000 from blacksmith) to be able to pass through the glowing door(from downstairs of the blacksmith, go outside to the woods, head left and then straight, kill some trees and follow the path around), and there's an illusion wall to a fireplace to the left of the glowing door. Run straight through without fighting and talk to the wolf in the other building to join the cat covenant. There's a big guy with a sword that you only kill once, thankfully, and you get that sword, don't cross them till you can take them on.
Right now I'm in Demon town, below Blighttown, trying to kill some giant minotaur that's bigger than the taurus demon and with a mallet, There were about seven-eight Taurus one's standing together, but they don't come back once defeated. The skull minotaurs, like the one you had to defeat to get the underground key do come back and are causing me the most trouble, in tight battle conditions. I'm going back for some poison arrows, seems to work on the giant minotaurs and the centipedes.