Dueling and training will be a thing in Elyria. What the exact conditions are have not yet been elaborated on AFAIK.
Exposition will be divided into 3 phases. For the first phase, no non-voluntary PvP will be allowed (dueling will be allowed).
For the second phase most crimes will be allowed including incapacitating other players (no coup de grace).
The third phase will be a free for all.
For reference: Exposition