You have left during a combat - what does it do?

Does it always add 1 to the deaths? and under what circumstances will this happen?

If u leave any game during combat, or (I think) 5seconds after combat, you will be given a death

It adds 1 death. In SL, when you shoot or engage in combat, you get a little blue face looking picture where your buff pictures usually are. While this picture is there, you are considered "In combat" and will get a death should you leave.

If u finish a duel and win, wait for the weapon to go down first, then u can rejoin safely.

I left the place because no one was there while my toon did an emote. Who knew crying can kill...