F.I.S.T.: Forged In Shadow Torch

This achievement is easiest done when using the whip. This is easy to complete at the top of Old Town location, find two drones and whip each until they're glowing, jump and perform both executions before touching the ground. It is possible that both drones may get taken out with the first execution. Luckily, there is a save terminal to the right. If you mess up, you will need to exit to the game menu and reload your save, this will cause the drones to respawn and allow you to try again.

Before anything, I'd suggest going to the settings, under game/execution and select "simple". This will disable the execution animation and keep things simpler and clearer. Double jump is also needed, along with the dash ability.

The location I used is at the very top of the Old Town map where you'll see a savepoint on the right. From that location, travel left and kill 2 guards: a light one and a heavy, hammer-type one. Stay behind the crate and use the enhanced punch (keep X pressed till your arm sizzles) to get rid of them. Make sure the drones don't start coming towards you. You will need two or three special punches to get rid of the fat one.

Once they are dead, move left again towards the drones. The trick is to be surrounded by them, not have both of them on the same side. The reason for this is, executing one too close to the other will likely end up in an unwanted explosion.

You need to hit the drones enough so they each start glowing yellow, then jump towards one of them, press B when prompted, jump again and/or dash towards the other one, press B again and have both execution animations unfold without ever touching the ground.

The major problem I encountered was that the execution prompts did not show when needed. I ended up falling back to the ground, missing the execution windows or executing one but not the other. That's also what lead me to disable the special animations.

My fist was maxed but worked better than the whip, which was also maxed, as one hit was enough to put the drones in execution mode.

I must have spent a good hour and no less than 50 attempts to get it. It is an absolute nightmare and yet another achievement that has no specific meaning other than piss you off for free since you will never execute 2 enemies in a row AT ALL during the game, WHY WOULD YOU.
I strongly recommend going for this achievement as early as possible during your run so you can try multiple times without having to grind like I did.

There is a second location for this that doesn’t require you to quit the game and reload.

Go right past the Old Town fast travel point, and when you get past the room that looks like an upside down “V” the first enemies you will come across are two drones.

Like the other guide says, try to use the whip, hitting each one twice, then executing both by jumping between them in midair. If you mess up, you just go back to the teleporter and go somewhere else, then come right back to make them respawn.

This location is also great for the achievement for knocking 20 enemies together in midair.

There is a second location for this that doesn’t require you to quit the game and reload.

Go right past the Old Town fast travel point, and when you get past the room that looks like an upside down “V” the first enemies you will come across are two drones.

Like the other guide says, try to use the whip, hitting each one twice, then executing both by jumping between them in midair. If you mess up, you just go back to the teleporter and go somewhere else, then come right back to make them respawn.

This location is also great for the achievement for knocking 20 enemies together in midair.