I think you are mistaken & the implied bad GM'ing is not helpful.
The outcome of the game is ALWAYS dependent on the GM, there's really not much else to say about this. It may not depend entirely on his/her choices, but it has a major impact on the game. Encounter design and running is entirely up to them, no amount of rules can save the game from ill intentions.
In the first example I chose a monster that should always be a dangerous big deal, it happens to also have a maneuver DC over what a strength build with a nat20 could achieve showing that a single dex save for such a powerful result is over the top.
Sure, but I don't see a reason for a Kraken to ever learn the Take weapon manouvre. It would make way more sense for it to just grab and swallow whole the PC, instead of focusing on a weapon he may barely be able to see.
In the second example I used a lich with trolls inspired by the War Trolls employed by the DoSK in eberron, surely plate clad weapon wearing trolls being used by a Lich qualify as monsters with significant martial training? It was an example though so I simplified it to troll bodyguards & a lich, is a lich not capable of plausibly employing guards with significant martial training?
Meh, I'm not sure they would qualify as monsters with significant martial training... Trolls are still little more than beasts, they normally don't use weapons and surely don't typically rely on finesse when fighting. They are strong and have phenomenal resistance, that's what works for them. A troll bodyguard with a plate mail would make for an even more phenomenal adversary, but I personally wouldn't give it any similar maneouvre.
The lich could easily have a humanoid bodyguard with such a training though, and it would be fine.
I may even let the lich steal a pc's favourite weapon, but I'm not a douche, which means that I would either leave open a possibility for them to track the weapon (another adventure and a real reason to passionately hate the lich), or I would find a way to compensate for the loss.
The point is not necessarily to hold the punches, but not to be a jerk. That's the entire point of the game IMO, the rest is just details.
In the third example, how would you answer Cindy's question without assuming the Narrator is a bad narrator? If you can't answer it wiuthout assuming bad GM'ing does that not present a problem that elevates Take Weapon into a disjunction adjacent redzone?
Honestly I'd simply agree with Cindy and suggest her to change group: if the DM is always creating encounters that directly sabotage the choices of a player, there's little else to say, it's a bad narrator behaviour. Or at least, it's a DM that cannot figure out how to make mildly different encounters, and a simple tier 2 maneouvre is enough to warrant a retroactive nerf of a class feature.
They were examples showing ways the ambiguities could cause problems, I simply chose monsters that fit the needs. Can you give examples with good monsters so we can talk about how the ambiguities create problems instead of attacking a hypothetical narrator?
There's never a way to remove all ambiguities, unless you're playing a purely mechanical game.
That's why so much of the fun or frustrations of the game come from the interaction between all the players, DM included.
Learning to play is way more than memorizing the rules and making an endless list of cases, interpretations and exceptions.
That bold bit is the problem with Take weapon, it does that to both PCs & monsters. There's no save on later rounds like control & debuff spells it's just a single dex save with a save or lose payload attached on the failed save.
It's not written explicitly, but other character can simply use the Disarm action and at least have the enemy drop the stolen weapon. Or they could grapple it so that it doesn't run away. Or surround it.
If the enemy tries to escape, you just got a different combat encounter, where a lasso or a net could have time to shine. Or you could have a chase.
If the enemy teleports away its a hard blow, but I'd ensure there's a good explanation for it to happen and some kind of follow up for the players (a good revenge can be more satisfactory than a treasure sometime).
You don't always need a mechanical counterbalance.
With Take Weapon "very dangerous enemy wielding a strong melee weapon" is unlikely to be anything but a dex based opponent sporting a raging pressed spiderbulb addiction & excludes the vast majority of monsters that would fall under that "some very dangerous enemy wielding a strong melee weapon" label. Fire Giant is a CR11monster sporting multiattack with a +11 to hit with a 6d6+7 Greatsword. It also has a +4 dex save, a level 9 PC is likely to have a dc17 maneuver DC it will need to roll a 13 or better to not lose that 6d6+7 weapon attack.
A medium character stealing a Greatsword fit for a monster of Huge size? I don't think so (o5E, and also LU, has unfortunalty very lose rules about the effect of size in most situations).
But even it did happen, the weapon would most likely be on the floor, unless the character is strong enough to carry several dozens of kg of steel with one hand. RAW that just cannot happen (see Oversized weapons).
But even if it did, it came to the cost of 2 exertion and the use of a class feature. It's GOOD! Let the character shine, and the frustrated monster find a way to recover it's weapon! Or not, maybe he'll just hurl a giant boulder to the PC. Or eradicate a tree and use a great club.