To get Damir to stay you got to:
At the start of the level when given the option to kill or knock out the man, choose to knock him out/spare him.
.Once you get the car and start driving towards your objective, you'll see a dismantled ship with slaves working on it. In that ship upstairs is a slave being beaten. Kill all the thugs upstairs and you'll gain a moral point. The slaves outside won't harm you so keep your guns holstered.
.When killing the guys outside the lighthouse you'll notice some injured thugs on the floor. Don't shoot them. Meet with Guil in the lighthouse and the moral point will flash.
.When in the spider infested satellite station. In one of the side rooms you'll find a framed picture of Guil and her family. Give the picture to her once you escape the spider infested lair.
.Meet with Anna. She will point out a dismantled ship where slaves are being held. Make your way over there (I would find somewhere to sleep to make it night time before heading there) and try stealth kill everyone in the ship if you can. Upstairs on the balcony part their is a lever that will release all the salves. Watch out for the heavy gunner In the back room. If you stealth it he will be sitting down making him an easy kill. Watch out for the two slaves laying on the floor. (Don't shoot them)
.In the Oasis level where you can earn:
I would try and beat the whole mission at night and stealthy. It's okay if you get caught and kill people. Just make sure none of the slaves are hit in crossfire.
On the top level of the area (bucket lift takes you straight there) their are two slaves locked up in a cage right at the back. Smash the lock and save them both to earn a moral point. The area is really small so you won't have trouble finding them.
.On the last level where you meet Damir and Guil. Damir will lift a grate to let you sneak in. Don't kill any slaves as they both ask of you. In this section its very easy to accidently hit one of them in the crossfire so time your shots if you don't plan to stealth.
.When you are walking to meet the Baron you'll see a thug throw a slave in a room ready to beat him. Go up behind the thug and knock him out to save the slave and earn a moral point.
At the end Damir will stay popping your achievement.Bad morals which will void the achievement are:
.Killing the man at the beginning instead of sparing him.
.Killing any slaves.
.When a thug surrenders, kill them instead of knocking them out will give a bad moral.