Overprepped logic also applies to Big Backpack. (both just half as strong as their counterpart).
Akimbo is still B-tier, it effectively gets the HP of the units in front of it. Works great together with Mages and a pure tank frontline.
Piercer is probably A-tier. It and the Hoplite are a lot more reliable than the Sprinkler and Javeliner, so I've had a better time making them my carry. Plus triple attack usually only needs 2 attacks to win anyway, after the first of which all dangers would be dead. (Or if they're still alive, you'd be worse off with the Sprinkler)
Knife Thrower is only 9 Rogues and costs 27 Gold (like any other Tier3). It's still the worst unit in the game. It would be a decent unit if it didn't die instantly. If you're worried about it being overpowered, make the bonus damage 100.
Living Weapon/Weapon Limbs are both weaker than their respective counterpart. Maybe B-tier, with some niche options. Attack buffs have diminishing returns: at that point in the game you probably want to spread them more evenly, rather than hyperbuffing the one frontliner that can already oneshot most things.
A lot of these units are ranked pretty nicely though.