Kill 20 enemies with your Equalizer while you have less than 25 health.
This achievement is not that hard to do if you are using the Equalizer as it was designed: as a last resort weapon. When you are worn down, out of ammo, and heavily wounded, you whip out the Equalizer and lay a beating down on your adversary. Once you hit the below 25 health mark, you will be moving as fast as a Scout and kill most classes with ease. You can rig this a little by rocket jumping twice, but it's not recommended unless you really need the achievement. Just get that Equalizer out and kick some butt.
To farm this achievement, get a friend willing to die 20 times while you are at 25 health. Easy as that. However, this achievement is also perfect to farm with Ain't Got Time To Bleed, as you will most likely kill your friend without having to respawn or heal yourself. Three kills and you get one achievement, 20 and you get another! If you friend is a Demoman, he can get The Targe Charge achievement by charging into you after all is said and done.
Note: Below 25 hit points, your damage and health increase will be capped, so don't tempt fate by going any lower. You're already easy enough to kill with 25 health, especially if any class lays a direct hit on you.
Assist a Medic in exploding 5 enemies with a single ÜberCharge.
Chance are, as a Soldier, you will have a Medic attached to you at some point. There are four main Medic targets, and they are (in order of importance): heavy, Soldier, Demoman, Pyro. Assuming there are no Heavies on your team, you will most likely have a Medic healing you as you get beat around. Once your Medic has an über ready, have him use it and make a major push. With any luck, you will gib (it has to be a gib) five enemies during the über and net yourself the achievement.
This has a companion achievement for the Medic titled Blast Assist, so it's an easy achievement to farm if someone is playing a Medic, does not have that achievement, and wants it. You'll need a Medic on your side and five cannon fodder friend (preferably Scouts) to kill on the other side. Blow them to pieces after the über triggers and voila.
Note: The title is a reference to the acclaimed bo9ok series, TV show, and movie M*A*S*H, which depicted a mobile hospital during the Korean War.
Death From Below
Kill 10 opponents who are airborne with the Direct Hit.
The Direct Hit is the primary unlock for the Soldier, replacing the Rocket Launcher. one of the more potent weapons, it happens to deal mini-crits to airborne targets as well as having rockets that are 85% faster, deal 20% more damage, and have a much smaller blast radius. This is the achievement to showcase the new abilities of the Direct Hit, much like Ain't Got Time to Bleed showcases the Equalizer. To get this achievement, simply shoot players while they are in the air. Alternatively, bounce players into the air and then shoot them. This is extremely easy given the Direct Hit's massive damage.
To farm this achievement, have a friend play a Scout and have him double jump in front of you. At a peak of his jump, shoot him with the Direct Hit. One mini-crit later and the Scout should be a spray of giblets across the landscape. This counts towards the gibbing grind achievement.
Note: There is a companion achievement titled Death From Above that should not be mixed up with this achievement.
Worth a Thousand Words
Provide the enemy with a freezecam of your 21 gun salute.
yet another taunting freezecam achievement. There's quite a few of these, with two being present for both the Soldier and the Demoman. The 21-gun salute is the new taunt for the Shotgun, and replaced the juggling taunt. Farming and doing this normally are one and the same, so you may as well just do it normally. Kill someone with the shotgun and press your taunt key. Assuming you aren't killed while taunting, you'll get the achievement.
Note: As we all know, a picture (freezecam) is worth a thousand words. In regards to the 21-gun salute, it's the traditional firing of weapons during a soldier's funeral, which makes it appropriate given your killing of a mercenary.
Brothers in Harms
Kill 10 enemies while assisting or being assisted by another Soldier.
This achievement is extremely easy given the post-update environment, littered with Soldiers and Demomen. Simply play as a Soldier normally, and chances are you will get this achievement in no time. The assists do not have to be in a single life or even a single round. The only requisite is that your assistant must be a Soldier. Appropriately, you can not be being healed by a Medic, as this will negate assists from anyone else, assuming you got the kill.
To farm this achievement, get a friend to play a Scout and another friend to play a Soldier. Every time the Scout spawns, both of you should unload your rockets at him. Do this ten times, and you'll get the achievement. Very easy and a relatively painless farm.
Note: This achievement title is a reference to the term "brothers in arms," which is used to refer to soldiers or any fighters united behind a singular cause. This was used as the title of a tactical shooter made by Gearbox as well.