OPTIONAL: DARK SUN GWYNDOLIN AND THE BLADE OF THE DARKMOON COVENANT
Go to the second bonfire in Anor Londo (the one you reach by lowering the main platform to its lowest level). Equip the Darkmoon Seance Ring you found in the Tomb of Giants and approach the statue pictured above. It will disappear, revealing a path.
Before passing through the fog door below, kneel on the carpet before it. You’ll be given the choice to join the Blade of the Darkmoon Covenant. Doing so immediately grants you the Blue Eye Orb (which allows invasion of any guilty player’s world) and the Darkmoon Blade Covenant Ring (which, when worn, will allow Gwyndolin to warp you to the world of anyone who has killed Gwynevere). If you do not wish to join the covenant on this playthrough, and instead would like the Soul of Gwyndolin (for weapon crafting and the achievement), proceed through the fog for a boss battle. Note that if you kill Gwyndolin, Anor Londo’s Fire Keeper will attack you the next time you enter her vicinity.
BOSS – THE DARK SUN GWYNDOLIN
You want to be able to run at full speed in this battle, so equip light armor. You’ll also want a weapon that strikes quickly and has decent range (a spear works great).
Gwyndolin only has a few attacks. His (yes, it’s a he) volley of physical arrows can be avoided by simply following a zig zag pattern. The mass of small blue projectiles can be avoided by standing behind a pillar, rolling under them, or blocking them with a good shield. The large blue orb projectile will pass through pillars and is extremely powerful, so your best bet is to roll away from/under it. You can tell when its coming by the slower charge time.
As soon as you get close enough to strike, Gwyndolin will teleport further down the infinitely long hallway. This is why you need a quick weapon; you’ll only be able to get one or two hits in before he vanishes.
Learn his attacks and have patience. This is an easy fight, relatively speaking. Just don’t get hit! After the battle, pillage the chests in the area ahead for the Miracle: Sunlight Blade and the Brass Armor Set.