If you did not take the biochip in Hengsha, Namir can be killed with two fully charged Typhoon blasts.
The fight is significantly harder if your augs are disabled. The rocket launcher and laser rifle both do heavy damage and are your best bet to kill Namir legitimately. However, there is a turret in the area before you go down the elevator to start the fight. If you dominate the turret so that it kills enemies, you can carry it with you to the elevator, and will easily kill him.