Choose any of the 3 new characters added in this DLC.
The Influential Governor
The Resilient Highlander
The Fearsome Coyote Man
You have to stun 3 enemies. When you are a "target", there will be people after you. When you find someone acting suspicious or obvious, quickly press to stun them. If they have also pressed the button you will get an honorable death instead. When you stun them, run off. It's best done in a team based game. Keep knives with you. If you see an enemy get stunned, you can quickly throw knives at him when he stands back up and stun him. This will be the harder of the achievements. Boosting would be your quick option here.
Non-Boosting Method: Your best bet is abilities. Assuming you are level 20 you should have a good amount to choose from. For example, place a trip mine at your feet and stand in a crowd. When it goes off stun and run. You can also use knives if you think you know your attacker before he gets to you. If on a team, sometimes you will get lucky and the attackers will be killing a team mate right by you and you can get a stun in. Chain it if you can with other enemy players or by using traps like a smoke bomb.
Training Method: Play the Training simulator from the menu (disc 2 only). Play until you get to 6/7 and you will need to stun a pursuer. During 7/7, you will stun again. You will get a notification to continue or to replay. Choose to replay and you will get the chance to stun a third time. This will unlock the achievement and is very easy.
Alternate Training Method: Play Introductory Session 3 which starts you off stunning people. Will be faster than any other method.