Renowned YouTuber MrBossFTW (aka Ross) reveals the secret location to access legendary power armour suit known as "Tessa's Fist", in his latest gameplay video for Fallout 4. In order to find this legendary armour suit, you need to head over to Quincy Ruins near Quincy Police Station, which is to the far southeast portion of the in-game mini-map.
Tip #1: It is advisable not to enter this location until you have cleared most of the other missions in the game and reached a high level ranking in the game.
Tip #2: It is recommended that you gear up with heavy weapons, power armour suit, stimpacks (medical kits) and a formidable companion to assist you in taking out tough enemy gunners at this location.
Tip #3: You may encounter several enemy boss-gunners with normal names such as Clint who wears a cowboy hat and a power armour suit. You will also come across a couple of other guys with randomly generated names and finally you meet Tessa face-to-face.
Tip #4: Tessa is the lone female gunner at the Quincy Ruins in a power armour suit. Once you have killed her, you can pick up the legendary armour suit that she is wearing, besides a bunch of Bottlecaps, Fusion Cells and a couple of Molotov Cocktails.
Tip #5: Tessa's Fist looks like a light armoured suit, but it has quadruple durability and offers 50 damage-resist points against melee attacks and bullet-impact damage, 25 hit-points against shock or energy damage, and 150 hit-points against gamma-radiation damage.
For further assistance, check out Ross's exhilarating gameplay video below: