Kill a Helghast within 1m with the M404-MAW M. Anti Tank Weapon ...and don't die
To unlock this trophy effortlessly, it is imperative that you play as Rico. He is a Hulk in regards to the damage one can take.
Load the second level of the fifth chapter, “Escape”, and grab the MAW on the balcony at the very beginning. Let the invading Helghast enter the trenches, but try and keep their numbers in check. If there are too many of them, you will only be making things difficult for yourself. On the other hand, if only one Helghast remains, it will be hard to score a direct hit with the Missile Launcher since they tend to move around a lot.
As you can notice in the video below, my first attempt was a failure when I tried getting up close with the Helghast. But, a little bit further, after having found a group of three Helghasts, it was easier to land a direct hit. Surviving is not a problem when you play as Rico on the easiest difficulty.
The M404 is the rocket launcher that has a support on the back of it, when you equip it look at the image of the gun and you'll see the "extension" on the back of it, a 90 degree "stick" coming out of it. The trophy is very picky, because you need, 1-Not to die, 2-Have the rocket hit the enemy, you cannot make it hit the ground or and object behind him, and 3-You need to be sure to kill only 1 enemy, you can kill more than 1 but ALL need to be 1m or less from you which is not always the case, so just hunt a lone prey.