Notes from author
For those who do not like the greatsword or do not like the claymore, the weapons Longsword, Broadsword, Bastard Sword, Zweihander, and Halberd are also good options. This is mostly for roleplay purposes, but it also is a good build for Fire Knights as far as I know. The preferred starting class is Warrior, as you need higher dexterity and strength to be at the lowest level that I know. You can use any spells that are Pyromancy, but the preferred spells are listed in the build. You must use the Astora Knight Armor, but the helmet is open for any type of helm or headgear. Preferably light headgear. Faith needs to be 30, to allow for greater protection against the magic of other spellcasters, and put in a couple of points into intelligence just to be safe. You must use either Charcoal Resin or Fire Enchantments for weapons, regardless of what the highest elemental stat is for the weapon. As for Roleplay elements, if you so choose to have them with this build, you must make an oath to always eventually light the first flame, to never harm characters, bosses, or enemies that attack only when provoked or otherwise (Example of this is Priscilla, as she is a boss that does not fight without you attacking her first, and Luiantus(?), who only fights you because he went hollow) and to defend yourself and your allies when you are provoked. Never become the invader unless either desperation is too great or someone has challenged you to a duel (a.k.a they invited you to play pvp), and when becoming the invader, always respect your enemy, meaning to always bow or respectfully start the fight, and when you have bested them, give them a proper warrior's respect. When an invader wanders into your world or the world of your summoner, never back down and fight to the bitter end alongside your allies.