|The following is based on Fallout Tactics and some details might contradict canon.|
You have cheated death! You gain perks more quickly as though you were still alive. Unfortunately you are now on death's short list! Your perk rate is reduced by 1 (the lower the perk rate, the more often you get perks), but you also have your HP reduced to a very low amount every time you level up. Ghoul only.
If you have this trait then the message "the Reaper's scythe smacked (character) around" will appear during level-ups and the character will suffer some damage. It is possible for a character to die this way.