What you may have noticed when fighting Fagnus is that he has a chest behind him. If you have an extra dynamite after blowing the rock in front of the cave, you can kill Fagnus and then blow up the lock on the chest to get his candle as a weapon. The candle is the second strongest weapon and deals 5-7 damage IIRC and is only beaten by "Sulfuras, Hand of Ragnaros" which is the weapon dropped by Sirath (Last boss of DF)