Nymphomaniac playthrough is not combat oriented. It is more oriented towards Whore Playthrough. To explain, you have to know about the sex attack in this game. When an NPC is raping Lona or Lona is whoring, you can press A,S,D,F to do Sex Attack. The keys = A is for vagina, S is for anus, D is for mouth, and F is for handjob. So if an NPC has their dick in Lona's vagina, you press A to inflict damage to the NPC. If it's prostitution pressing the correspondent key increases the the money gained. Because the Nympho trait increases sex damage a Nympho character can one shot kill NPC during rape (it's very much possible). There is also in-game tutorial notes about sex attack that you can pick up. The note is in the toilet on the second floor of the first tavern.
To summarize, a Nympho is the weakest in head on combat since it doesn't have the raw strength of the warrior build or overwhelming magic attack like the mage build. But it is fun to be able one shot kill rapists with just Lona's "holes" or handjob.