I got the Demonbrandt basically as soon as i could beat that red-eyed soldier on the bridge (which was about soul level 10)

first, find the crossbow (or get a bow later in the game), and buy lots of bolts/arrows, or get some magic (of you don't start out with it in the first place). Now find a thief's ring (which you can find on the platform where you first meet Ostrava, or if you kill patches) and then kill Ostrava (or wait till world 1-4) for the Mausoleum key.

next, go to the mausoleum and kill the red-eyed soldier and open the door, and now make sure you have a LOT of time. (and make sure you have a thief's ring equipped)

target Doran, and shoot him with either a bow or magic, and when he comes towards you RUN AWAAAAYY!! to the bridge (you dont even have to pass half way), and when he starts to walk back to his first position, run up to him and give a good stab to the back, and run away again.

just repeat this over, and over again and soon (when about not even a third of his health is down) he will say that he is impressed or something and you can go get the Demonbrandt without him attacking you.

yaay you now have a really powerful weapon early on which will make things so much easier for beginners ^-^