The developers always give you an out...in addition to the bones mentioned...you can always get back to your bloodstain (guaranteed) if you wear a ring of sacrifice...even if you die a hundred times your bloodstain will still be there and you can get it as long as you wear the ring. You can even put it on after you die and even if you die again the stain will still be there. That siad humanity and souls are easily farmed and the amount you need ot get your sword going is small to be honest..particularly of you enjoy mulitplayer....just help others do their boss and reap the rewards.
Oh but you do! YOu get a titanite SLAB for killing him...only one of two guaranteed per playthrough and the second is incredibly easy to screw up...can't max regular armour or regular and lightning weapons without it.
Like many bosses its all or nothing with stray demon....takeoff all heavy armour so that you can roll at <25%, two hand your weapon, and just stay behind him in order not to get hit....only go in immediately after he does
that AOE shot (which is magic not fire so if you actually do want to block or protect against it its MAGIC protect you need...but this is not recommended.) So go in give him two shots then retreat behind him again...rinse, repeat, get your slab and feel the maxed out glory which in your case ....who are we fooling?.......will be your lightmore +5.
Same as any enemy in souls...patience. I strongly recommend taking them on one at a time. Use a stable shield to circle strafe them and then backstab....they are incredibly quick to combo and basically kill you in one flurry...so do not get cocky and take them on trading blows...you will lose that style of battle a majority of the time. several of them can be dropped on from above, adn several can be snuck up on form behind...that's about as much creativity I will recommend...they are just really dangerous things to fight and to farm them means sticking to what works.....circle strafe backstab x2, on to the next. As an aside, they are known to rarely drop a SLAB...has never happened to me in over 1000 hours of souls...

I do however get lotsof dark hands to give out to noobs in firelink when they summon me for help...they thinkits sooooo cool...lots of bang for the buck forthe "white knights" amoung us.