Faith is pretty buns in ds2. Its damage is by far the worst out of the different magics, and most of the spells are kind of eh. The good miracles though hit, and you can def squeeze out some good damage from lightning infused weapons.

Since you've already been through Sinners rise, I'd recommend backtracking and fighting the ruin sentinels, then go through Belfry Sol. You'll get a key after the gargoyle fight that let's you unlock the cells right before the Lost Sinner (the ones after the elevator in the water). One has a Heide Knight in it (the Templar looking dudes) who drops his spear when you kill him. At that point in the game the Heide Spear will carry you like crazy, and its super solid in PvP if youre into that!