Start as Cleric or Sorcerer for the attunement. I chose Cleric, for the better dex and strength. This build works pretty well in both PvE and PvP, and can do some pretty heavy damage if played right. This one requires a pretty cautious player, however.
I used the Full Moon Sickle through the entire game once I got it. Infusing it with bleed is optional, as it already has inherit bleed. Feel free to experiment with some other bleed weapons.
I used the Executioners set with my playthrough of the character. Though the Bone King set and the Tattered Cloth set looked pretty good as well. If you happen to play this build and find any good combinations of equipment, please let me know.
And for rings I used the Crest of Blood, the Red Tearstone Ring, the Southern Ritual Band +2 and the Ring of Blades +2.
Fire Orb, Great Fireball, Fire Tempest/Chaos Firestorm, Great Combustion, Fire Whip, Lingering Flame, Flame Swathe, Forbidden Sun. Any powerful offensive fire spells, really.
This build can dish out some pretty good damage when played right, but physical defense isn't exactly a strong suit here, especially without a shield. The trick with this one is to dodge all the time, and try and get in as many hits as possible. Save pyromancies for bigger windows of opportunity to attack. This build does take quite a lot of damage in fights, which is what the Red Tearstone Ring is for.