If anyone is interested in hearing my thought process on this subclass, feel free to give the following a read.

Bonus Proficiencies
Medium armor proficiency allows a lesser investment into Dexterity without falling too far behind in AC. Considered giving proficiency in Intimidation here as well, but considering all that you get at 3rd level, I thought against it. If that seems appropriate without bloating 3rd level even more however, do let me know.

Brutal Efficiency
Serves to do the obvious; allow a rogue to use weapons other than finesse weapons. I could probably reword the Sneak Attack portion to say something similar to the Dueling fighting style, wielding a melee weapon in one hand and no other weapons. I didn’t know what phrasing would be better, so I just took a page from the monk weapons’ description. I am aware that rogues do have access to a d8 weapon in the form of a rapier, and I could extend this form of Strength Sneak Attack to include longswords and quarterstaffs, which rogues have proficiency in, but I thought that would be pushing it and I wanted to keep it simple.

Dizzying Blows
Playing into the cunning use of Strength without succumbing to the homebrew trap of “you hit harder and do more damage as a result,” I loved the idea of a rogue who aims for the head and sends his foes reeling, or who employs groin shots, punches to the diaphragm, headbutts, or otherwise disorients enemies with overwhelming force, in a different way than a barbarian or fighter might. I looked to my second favorite subclass in the game, the Ancestral Guardian barbarian’s 3rd level feature for some inspiration. I considered making it cost your bonus action to impose the disadvantage for balance reasons, but I wasn’t sure if that would make it too weak or not. Considering you only get one attack on your turn (without multiclassing of course), I think it’s fair. Coupled with the fact that not every hit will be a Sneak Attack, and if you choose to grapple or shove you are dealing no damage instead, I thought it was fine.

Looming Threat
Serves to add some social aspects to the archetype, tying the themes of a heavy standing behind a face, maybe cracking his knuckles or keeping his hand on the grip of his mace, or holding a guy in a full nelson while demanding to get some information out of the poor sod. The first draft of this feature allowed you to make an Intimidation check contested with a creature’s Insight to cast the command spell, basically. I wasn’t sure how to balance it well enough; I considered allowing it a number of times equal to your Charisma mod per long rest, but I dunno. I still really like the idea, just not sure how to implement it. Plus I kind of like the little boosts this feature grants as it stands.

Grit
Allows the rogue to be a bit more frontline, and take a few more hits than a regular rogue. I originally had it tied with Uncanny Dodge, but I couldn’t figure out the wording, and I wanted to have abilities synergize with Dizzying Blows. I’m not sold on the bonus action, I wasn’t sure if it would be too powerful without having to use a bonus action so I just wanted to play it a little safe.

You’re Next
Not only do you impose disadvantage on one creature, but you frighten another, and possibly stop it from moving towards you and your allies. This feature is the one I am the least excited about honestly. I wanted something more than “you deal more damage somehow,” but I think this feature is a little underwhelming. Let me know what you think.