Atton Abuse
Where? - Anywhere ; When? - When you have Atton with you
This is a nice trick. You will need to turn on solo mode first, then send Atton to slaughter your enemies. Even if Atton gets knocked out he will awake again. Atton will eventually take care of any enemy with the other two just relaxing.
I've Killed Handmaiden! 
Where? - Ebon Hawk ; When? - When you have Handmaiden
When you duel with Handmaiden there are surtain rules! If you brake them the fight will be over. However, if you brake the rules between the fade in and the start you will need to eventually kill her to get out of the room. There is good news. She will return when you leave the Ebon Hawk. You can also take the items of her corpse and duplicate them that way.
I'M NO WOMAN!!!
Where? - Anywhere ; When? - When you have the dancers outfit
When you have the dancers outfit and you're male it will satate that you can equip it even thou you're not a woman and that you can't equip it.
To be continued...