Often players have a initial duel config similar to a mercenary config usually with reasonably balanced defensive(often in the form of mobility) and offensive abilities.
Once the first kill occurs the loser will often tune their config to defeat the winners. They will have an advantage in that they know what they are buying to defeat. So the gear is customised constantly to beat what the winner has, often swinging from offensive to defensive.
Injury is often the main score of consequence in duels between evenly matched opponents.