It used to be that if X and Y were involved in a PK situation, and X had logged in more recently (or linkdropped and reconnected), X's swings would come first in melee, and Y's would come after.

That has been changed to the reverse, making it even more beneficial to remain logged in. This coincided with the WHO list becoming 'flipped', showing characters at the top who had been logged in longer and more recent logins at the bottom.