A way for players in the PvE environment to fight each other consensually. Players from opposite factions can duel, but the mechanism is primarily for dueling players of the same faction.
How do I start a duel?
Right-click on a player's portrait and select the "Duel" option. A Duel flag will drop from the sky, and if the other player accepts, a countdown will start showing the time remaining before the start of the duel. The circle around your opponent will turn red, indicating that the player is now hostile.
Another option is to type "/duel" while having the target you wish to duel both targeted and in range. This may be more convenient if you wish to create a macro for this function.
Dueling etiquette
Some behaviors during a duel are considered bad form or impolite (also known as bad etiquette) and some are considered good form.
Some examples of usually frowned upon behavior:
- Requesting to duel another player at a much lower level than yourself.
- If you want to duel someone just to "Test a new ability you got from a trainer," at least duel someone around your own level; you won't be using that new ability on mobs or players that are 30+levels under you, you'll be using it on things that are actually a challenge (using a new ability on someone that can't possibly beat you only makes that ability seem much more powerful than it really is).
- Drinking any potions during combat.
- Having an ally buff you before combat.
- Using very long cooldown moves during duels
- Running behind buildings or large obstacles just to buy time.
- Repeatedly requesting another duel if you lose (or win).
- Randomly asking people to duel, especially when they are obviously busy with something else (like checking mail, exercising some profession to make something, or fighting a mob).
These points are disputed among players. Discuss your opinions on the talk page. If you are having problems with any of these issues, make sure to discuss the points of your duel with your opponent before beginning.
Some examples of good behavior:
- Asking your opponent if they want to duel and getting their agreement before selecting Duel from their portrait.
- Letting your opponent buff up before you start.
- Healing your opponent after you defeat them.
- Taking aggro off a defeated opponent who gets attacked by a mob after they lose.
- Praising an opponent or giving them a positive emote when you lose.
What ends a duel?
Generally two things will end a duel:
- A duel ends when one player is very near death.
- The system will announce the result of the duel: <winning_player_name> has defeated <losing_player_name> in a duel.
- While rare, it is possible to die after a duel with a same-faction player. This usually happens with mistimed damage from a warlock DoT. No honor is gained nor does the death cause durability damage.
- A duel also ends when one player moves too far away from the Duel Flag, usually due to running away.
- The system will announce the result of the duel: <fleeing_player_name> has fled a duel with <remaining_player_name>.
You can use /forfeit or /yield to end a duel if for example you agreed to one by accident, or some other circumstance dictates you need to leave (mob spawns and attacks a player)
Dueling in Contested territory on PvP servers
It is generally discouraged to Duel in Contested territory on PvP servers. If you do decide to duel in contested territory, beware of enemy factions and their proximity to you. If you are both low on health and an enemy player shows up, it's two free Honor kills for them.
Dueling in Contested territory on PvE servers
Players of opposing faction can duel, but be careful of the opponent switching on the PvP flag during the duel, as hitting him will make you PvP-flag-enabled. When this happens, you are attackable by anyone in his faction who may have been waiting for a chance to gank you.
What does winning a duel mean?
You win. You get glory (the system announces that you won). You don't earn XP, 
[Honor] or an opportunity to loot, you just get the satisfaction of knowing that you were able to defeat another player and possibly gain some experience at fighting other players that you will be able to use in the various forms of PvP combat. Sometimes players wager bets on duels, which means that you can earn (or lose) gold from dueling.