I want to start out by saying that I agree with combat timers existing in this game. Due to the nature of different zones, a player running from combat could far too easily escape simply by moving to the next zone before his pursuers.
I really enjoy the effective range and sight range mechanic. It allows for players to gamble at a lucky shot to potentially kill an enemy that would normally be out of range. A player can shoot as far as he sees and often at the end of his sight range the chance to hit is 0%. The issue with this, is that shooting at an enemy with 0% chance to hit starts their combat timer.
This means that a player is locked into the zone by a player with 0% chance to hit, making it impossible to leave. This probably hasn't happened much (I have killed a few players exploiting it, I admit) due to the small scale of players. However, with more players and heavier PvP I could see this being a very big deal, and a very problematic exploit.