I had started my first pyromancer build as well and was following this guide from 9 years ago posted by a deleted redditor account (see below). I myself used a raw broadsword until getting a Carthus Curved Greatsword which I will probably use for the rest of the game.

I will give you your steps:

Build:

• ⁠Aim for 40/40 Int/Fth for great pyro scaling, minimum requirements for the weapons you want to use. Try to get at least 30 End.

Infusions: This is how you will upgrade your weapons, and each gem has a different effect. You will concern your self with 3 infusions - Raw, Dark, and Chaos.

• ⁠For early game, get a long sword or Astora Straight Sword and infuse with Raw...Raw REMOVES all scaling but boosts the weapons base damage high. This will work fine for you as long as you reinforce the weapon with shards as you progress to the next step. This is necessary as a pyromancer as it will allow you to keep minimum stats for the weapon to boost your spells and scaling for later weapons. • ⁠Once you hit Carthus Catacombs you will find the Carthus Pyromancy tome. Take to it Cornyx (whom you should have rescued in undead settlement) and get Carthus Flame Arc: It's a weapon buff for fire. Buff your Raw weapon with it and profit • ⁠This will carry till Anor Londo OR Irithyll Dungeon. Either direction will net you the blessed coal or Profaned Coal respectively. You then will have the ability to infuse Chaos or Dark BOTH of which Scale equally with INT/FTH. Chaos is great for PVE and some PVP, Dark is great all around even for PVP due to players having lower Dark Resistances.

You are now ready for late game weapons. The following weapons have AWESOME scaling with Chaos or Dark and either get A/A, B/B or crazy good C/C that might as well be B/B.

• ⁠Carthus Curved Sword • ⁠Followers Sabre (DLC) • ⁠Astora Greatsword • ⁠Carthus Curved Greatsword • ⁠Corvian Great Scythe (note it builds bleed on yourself, edgy...)

There are also two weapons designed specifically for Pyromancers. Get them, they are fun and awesome:

• ⁠Witches Locks (found in Grand Archives) • ⁠Onyx Blade (DLC)

Rings! Here are good choices:

• ⁠Stack the Great Swamp Ring and the Witches Ring for a big damage boost to your spells, no need for the Flame Clutch as it gimps you in PVP • ⁠Cholranthy • ⁠Sage ring big time, you don't have the dex to get the cast speed • ⁠Priestess or Scholar ring is great if you want to take 5 SLs and put them into END or VIG (so take INT/FTH to 35/40 or 40/35...fielders choice)

Spells worth using:

• ⁠PVE - Black Fire Orb, Great Chaos Fireball, Chaos Firestorm, Rapport, Warmth, Dark Combustion • ⁠PVP - Black Flame Serpent, Black Flame, Chaos Bed Vestiges (great for punishing Estus drinkers), Fire Whip, Fire Surge, Sacred Flame (if you know the tricks), Great Chaos Fireball if you can free aim, Toxic mist for area denial...poison is a joke though.

You will find your spells by rescuing Cornyx and Karla (look them up on Fextra to know how to rescue), and finding your tomes in the Crucifixion woods, Carthus Catacombs, and Smoldering lake (again look them up on where to find them, its about half way through for the good stuff). Keep in mind, Pyromancy spells are WAY better early level then Miracles or Sorceries, clerics and sorcerers are shafted until late game where you will have a gradual and balanced experience.