Advice for anyone trying to tackle the Titanite Demons.
Best option if magic is not your forte is actually Melee, you just have to know where to stand.
The trick is to stand next to his left (missing) leg and rotate counter-clockwise, this will allow you avoid his magic (he won't use it) and melee (he can't actually hit you). The only thing you have to watch out for is his leap attack, however you can just roll in pretty much any direction to avoid it.
Arrows might be safe for 1-2 of the demons but for a few it's nearly impossible due to their locations and they health goes up impressively towards the end of the game, meaning it will take a hell of a long time and a lot of arrows. The melee method is slightly more risky but only marginally and is considerably faster.
Moonlight Butterfly tips:
Easy boss if you again, know the trick to it. The boss has 4 attacks, each having a very similar method for avoiding.
Fast Soul Arrows: Roll towards the boss and into the wall as soon as they fire (noise cue is the most reliable telegraph)
Slow Soul Arrows: Wait and roll to the side when they get close.
Explosion: Simple, when the boss floats down to the wall and presents its ass for a whoopin, it will eventually cause an explosion, easy to avoid, no tip required.
Beam: You may not always see this, depends how fast you are, the boss may at some point do a funny beam attack, best way to avoid this is to just leg it to the end of the arena which is furthest away.
I can give tips on request if anyone needs them, I know the game inside out. Helping people is a nice justification for the ungodly amount of hours I've put into the game.