Ornsteins Spear Is the only one that comes to mind at the moment.
His spear may have good letter scaling, but the actual results for a faith build are pitiful. From 8 faith to 40, the lightning damage increases from 100 to 179. The majority of its damage comes from the physical side, which scales with str/dex. When two-handed, a 16/24/40 DSS sits at 432 AR (253 phys, 179 light). A 27/40/8 DSS sits at 435 AR (335 phys, 100 light). Yes, their ARs are similar, but due to how the damage formulas work (it's not simple subtraction), the second will actually considerably outdamage the first on most enemies, if not all.
And of course, there's the fact that you need 24 dex to wield it, which goes against his wish to leave dex alone. Numbers tirade aside, I'd agree with Nash. Just find something you like and upgrade it. There aren't any super awesome faith weapons like the Moonlight sword for int.