People were asking for examples of Stains. So I'm providing a few here. :)
Temperamental- You easily fly off the handle.
Psychological Addiction- You are addicted to something. This is not a physical addition like a drug, but instead pertains to psychological needs, such as eating or stealing things. Not being able to satisfy your addition can lead to depression, listlessness and other psychological mood disorders.
Nightmares- You suffer from nightmares that don't let you get much sleep. These nightmares happen on a consistent basis and can be reoccurring.
Macho- You have a need to prove yourself to other people and may well do stupid or insane things to prove your courage and strength to others.
Absent Minded- You have the mind of a sieve and tend to forget things. The higher one takes in this flaw, the more absent minded the character is, from mildly forgetful to completely unable to remember something just a moment later.
Weak Willed- You are very easily manipulated and susceptible to mind control and coercion. The higher one goes in this power, the less backbone and willpower they have.
Naive- Gullible and easily fooled, you are not weak willed, persay, just not worldly enough to know better. People are more able to convince you of things, even if they aren't true. You are blessedly trusting, and that can be abused rather easily.
Attack Restriction- There is a certain class of people that you just cannot bring yourself to harm in combat, no matter what the situation is. Lower levels in this failing mean the character will fight reluctantly, whereas the highest level renders the character unable to fight against the restriction at all.
ADD- You suffer from Attention Deficit Disorder and are easily distracted from any task. Lower levels in this failing indicate the character has some ability to keep on track where as higher levels are-- oooh... shiny!
Dark Secret- You have a skeleton in your closet and it's one that would cause you a lot of grief if anyone ever found out about it. The level taken in this indicates the severity of the secret. Low levels indicate the secret is troubling, but not enough to keep the character awake at night in a sweat. Higher levels mean the character will do anything to keep the secret from coming out for it may well ruin him/her.
Phobia- A phobia is an irrational fear of something. You fear something, even if everyone else wonders why you're freaking out about it. This can be anything from a fear of spiders to a fear of being out in open spaces, the choice is up to the player. The level taken in this indicates the severity of the phobia. A low level means the character will feel mild sensations of panic, but can usually endure. Higher levels mean the character will go into a panic attack if ever in the presence of the phobia.
Amnesia- You suffer from amnesia, and cannot remember who you used to be. At the lowest level, the character may have flashbacks of who s/he used to be while at the highest level, the character simply knows nothing of his/her past life, whatsoever.
Lost Sense- You are without one of the prime senses. Sight, smell, hearing, etc.
Drug Addiction- You are addicted to a drug of some sort. This could be something as benign as caffeine to something much more potent and life threatening. If taken at the highest level, you will suffer severe withdrawal symptoms and possibly die without the drug.
Ageism- You are either very young or very old, enough so that it is noticeable. At lower levels, you're likely either just at middle age or younger than the legal drinking age. At higher levels you may be elderly or a young child. (This doesn't necessarily mean you really are that age, just that you look the age.)
Physically Unfit- You are not an athlete by any stretch of the imagination. Just having to sprint across a hallway may wind you and lifting more than ten pounds will be difficult.
Sickly- You have never been very well and tend to catch anything that comes around the corner. You may have something like asthma or an allergy that always plagues you.
Slow Healer- You don't heal very fast and wounds take twice as long to heal than normal. You can only recoup half of a healing spell's potency.
Disfigured- You have a nasty scar that easily marks you and is recognizable. The disfigurement is somewhere always visible, unless you cloak yourself from head to toe.
Paraplegic- You cannot use your legs and must be transported around via wheelchair or carried by someone else.
One Eye- For some reason, you only have one working eye. Either the opposite eye is gone, or just completely blind, you are now hampered with depth perception.
Crippled- Your body is somehow unable to function normally. Perhaps you are missing one arm, or you cannot use one of your hands, etc.
Directionally Dysfunctional- You have no idea where the directions are and wouldn't be able to find your way around without landmarks. If someone asks you which way is north, you're just as likely to point west.
Bad Reputation- You're known for all the wrong reasons. People know your face and it's difficult to go anywhere without someone knowing who you are.
Stigma- Unlike Bad Reputation, no one immediately recognizes you, instead they just 'sense' that something about you isn't right. People may give you a wide berth or avoid you all together. Salespeople may decide that you're not worth their notice, etc.
Magic Vulnerability- You are vulnerable to all magic spells, they're likely to cause more damage to you and status spells have a higher chance of actually succeeding in putting a status effect on you. The higher you take this Stain, the more vulnerable you are. At the same time, beneficial spells are more potent on you as well.
Elemental Weakness- You are vulnerable to one of the elements. When spells or powers involving this element are used on you, they are going to cause more damage than usual on your character. The higher a level you take in this, the more damaging this element is to you.
Status Weakness- You are weak to a certain type of status effect. When spells or powers involving that status effect are used on you, you're more likely to end up with it affecting you.
This isn't a cut and dried list. It's just to give people an idea of what they can do for Stains.