I think this is definitely a person preference thing. I prefer 'normal' swearwords generally, just because I know what they mean and I know the context in which they should be used. The Tiefling swearwords are fine, but they just leave me with a general sense of 'oh, I guess that was a naughty word' as opposed to someone saying "Oh, Fuck yeah!" when I agree to help them. I understand what that means, and what it means for someone to so casually say it to a stranger. The immersion breakers for me are when people keep spitting out variations of 'By Odin's beard!" or "By Zeus' hangnail!" It always makes me pause for a second and consider if what they just said was supposed to be blasphemy, of if it's just a general accepted exclamation. Is it even offensive? It's especially strange, because people tend to use the deity they actively worship in their expletives, which is generally considered disrespectful to that deity. Saying 'God damnit" in a medieval temple would get you tossed on a torture rack, but you year paladins, clerics, and peasants alike using their god's name in vain all the time. What does it even mean?
