Which deals more DPS? Or is overall better?
Silent Nightblade or Faust?
Silent Nightblade has more DPS but less damage per hit. SN can also be charge spammed because it doesn't slow you down while charging and doesn't leave you super-vulnerable after you use the charge attack. Also, since you often won't be using the 2nd swing on a Faust (because it leaves you so vulnerable), SN's DPS is comparatively even higher. It's true that SN has slightly less reach and knockback, but if you can't kill slime and gremlins without more knockback, something's wrong. Personally I'd go with SN (as it's what I have).
if you're choosing these 2 swords cuz you're gonna do jelly runs, nighblade to get you there, faust to use on jk~ only time i pull my faust out on a jelly run is usually by mistake or to hit the lumbar in hopes of cursing him.
Personal preference. Different fighting styles, different weaknesses, etc.