you're tripping and don't understand how to read historical accounts nor understand how physics and biomechanics work to say such a thing, more importantly, you don't understand the evolution of draw weight and the fact that Longbows (capable of piercing mail+gambeson) didn't exist prior to the era covered by that video, and that once they appeared, full plate start being manufactured to counter specificually that.This is a big exaggeration and goes straight against many contemporary sources of the time where plate armor was used. Which was not in use in the 11th c. AD which seemingly is kind of a model for BL Calradia. So even if you were right about the impenetrability of plate armor (which you are not), it would mean not much for the BL timeframe.
There was hardly any hardened steel armor in the early late medieval ages, judging from the few surviving example, so assuming it would have existed in the early high medieval period is not convincing. There was not even much mild steel armor, most armor was made from iron. Steel and iron of varying quality, far away from what we use today, even in the best made tests.
If we assume that late medieval plate armor was used, your conclusion is also wrong. An arrow from a medium powered war bow (let's say 120 lbs) or a similar powered crossbow (let's say 800 lbs) or a javelin of about 0.8 to 1 kg weight may not have been able to penetrate a breastplate or the front side of an helmet, measuring about 1.5 to 2.5 mm. But it could probably penetrate the arm and leg armor (often 0.8 mm or less) or the sides of the helmet/visor (why else tell the sources about the fear of knights about it?).
A men-at-arms in plate armor shot through the arm or leg would be out of combat or greatly reduced in his effectiveness. BL cannot simulate this. So the armor cannot be modeled after isolated tests of the effectiveness of the most effective armor pieces alone. That's the same as creating a modern video game tank by giving it front armor strength all around.
BTW I wonder why there were projectile weapons in use in the medieval age and castles constructed to bring bows and crossbows into best use if a well equipped army could nullify the effectiveness of ranged weapons?
Wether archers in the game are able to kill an armored unit in 4 or 6 or 8 or 20 shots, I do not care that much, because I hope it will be moddable (f.e. with mods like Modifiable Armor Modifiers or Custom Damage, sadly not up to date), so anybody can do his/her thing. It's more about feeling because arrows/bolts/javelins don't tear down people's health more and more in reality, so we don't have examples how strong a bow has to be in the game. It's arbitrariness.
The main reason for the creation of metal made armor were arrows, because in the past you could deal with being unarmored or even lightly armored and fight on melee distance relatively safe by appropriate use of technique, that's the main reason armor was abandoned once gunpowder started beating it too often. It was too expensive and too inneffective for it's purpose. Arrows were harassment tools after the creation of armor in general, yet there are accounts of successful ranger employment due to them being extremely well trained and precise, capable of basically shooting gaps, as bows increased in technoloogy (up til the longbow era), their draw-weight penetration power was countered by making armor with more resistent materials and designs.
Now let's explain some things pertaining fighting and biomechanics:
Any martial artist has thorough knowledge of how fast we can move and how sharp our reflexes get with extensive training. A well trained warrior during the middle-ages would be able to dodge and even catch flying arrows without much issue unless the arrow was accelerating. Given that fact, extreme ranges for bow usage were a waste of resources, first everyone would see the arrows coming seconds before they were even a threat, second they would brace for the arrows employing the use of any shielding they had (be it shields, or even a helmet that is impenetrable, or even a shoulder pad, whatever they had in hand). That means bow usage was done at closer ranges, something between 50 to 10 meters distance, meaning that archers would be almost indistinguishable from infantry during a battle, they'd be mixed up there shooting through opportune openings on their own formation, or strays from the enemy who got past certain lines or directions. The most obvious on a defensive strategy would be to deploy them right in front of the infantry and have them retreat as the enemy approached, same for attacking but they'd skirmish and fall back and have their own infantry's back.
Another interesting thing is that if you are going to get hit by something, and you are proerly trained, you'll reduce the force of the incoming blow by mimicking it's motion direction. So if you are hit by a punch from your right, you'll move your head to your left as it's about to hit, reducing it's impact effect. Given that arrows can be foreshadowed (seen coming), anyone would move either completely avoiding the arrow, or reducing it's impact force. Add to that armor protection (mail + gambeson) and the fact that bows prior to english longbows had a draw weight up to what? 80lbs to 100lbs max? That's not enough to penetrate most armor. Aside that factor, even after being pirced by an arrow there's no "bullet" effect, if it didn't server an important artery or tendon, the person shot can still fight as if nothing happened (although with a lot of pain). Given that they'd be wearing mail + gambeson, that means the penetration, even if happened, wouldn't be deep enough to incapacitate the person, and the draw weight of old & common bows wouldn't be enough to break any bones.
There's a massive issue of debating this kind of subject because a lot of it wasn't properly accounted for in registries of the time (probably too obvious for them to bother, nobody would've imagined we'd be all lazy ppl eating mcdonald's), and most historians are just couch-potatoes who don't understand the first thing of how the human body works and how the mindset of a fighter works, nor do they understand most basic factors of biomechanics and innate psychological reactions of people under a fighting situation. The best people, most qualified, to really talk about this would be historians who are also black-belts in martial arts and have done high-level competitive fighting, preferably MMA fighting along with HEMA. Those guys would be able to give a even better and more thorough explanation, yet I've never seen nor heard of any historian who's also a high level fighter. We do have many HEMA history buffs but those guys tend to agree with me (us, because we are many who say what I'm saying here) and as me, they also recognize that we can't know everything, but that "simplistic" mindsets about ancient warfare are just a mistake, a stinking one at that. In conclusion, bows could be lethal, but mostly weren't, their lethality depended on luck or extremem skill to bulls-eye armor gaps and slits, or opportunity shots to catch people unaware and/or off-guard.
The reason that heavy bows didn't make it for most of medieval history spam isn't even a lack of ability to produce them, but rather a lack of people able to use them. If you look at it closely, all 100+lbs bows in history were only used by bow-centric cultures like the Mongolians, the English Longbowmen under the Normans (and even than long after the establishment of England itself), etc. Low weight bows aren't very effective in general, but the common hunting bows (50–60 lbs) were the most used throughout European history for warfare too, I'd wager there were ones a little bit heavier, but not by much.
So in terms of M&B balancing, for the best experience possible when you're simulating medieval warfare, you need to weaken bows significantly and only allow OPness on special units like Fians, or Khuzait t5 - t6 units. Any other bows from lower tier units should do nothing against t5 and t6 armor, and have it's dmg significantly reduced for quality low tier armor in general. The reason, main reason, why balancing feels off for most of us (probably you included) is that they've mixed techs and inserted hollywoodian tropes into the game, so warfare feels exceptionally uncanny, and it's because it is. They've also mixed different era technologies which also doesn't help much, and made disgusting mistakes like inserting "leather studded armor" which doesn't exist, that would be a Brigandine, which's a type of plate armor.
So let's classify armor types for better understanding:
Cloth -> Clothing wasn't armor and provided no protection
Reinforced Linen: Aketon / Gambeson, etc. -> Provided protection against cuts, slight protection against piercing and good protection against blunt force trauma.
Mail: Full protection against cuts (no sword can cut through mail) and significant protection against piercing (not full). Mail was rarely used without a gambeson underneath for many reasons, including how uncomfortable it is to use it without it.
Plate: Full protection against cuts, full protection against piercing (if hitting the plate face on), no protection against blunt until Full Plate Cuirass was created, which protected your torso against all of those.
So how did they kill? Technique and weapons capable of applying massive weight force, but mostly (almost all of them) would first be thrown into the ground and than stabbed through gaps with a dagger.
"But how did they kill in open battles?" Well, mostly they didn't, the losing force would almost always surrender and the winning force would do everything in their power to treat the wounded and keep them healthy and alive because RANSOMS WERE MASSIVELY SOUGHT, and most nobles were related to each other.
Big casualties only started when professional standing armies started being used at late medieval era. Battle casualties in the pseudo-era of Bannerlord were a rare occurence, and when a battle caused those, most would be from wounds much later, not during it.
Because it was impossible to field a full army of top armored people, one armor piece would cost something like modern day 5 million dollars. Thrown in a full set that would cost something like 20 million... Most of the troops used what they could afford or their lord could afford to provide, which was gambeson for most of the time, than richer soldiers or specialty ones, during the plate age, would be using mostly mail + gambeson, and a brigandine vest along with it at best. Levies (the 80% composition of a large army) would be weaponized farmers, they wouldn't wear much protection other than a helmet. In fact, even the lowliest of peasants would often wear helmets for obvious reasons.BTW I wonder why there were projectile weapons in use in the medieval age and castles constructed to bring bows and crossbows into best use if a well equipped army could nullify the effectiveness of ranged weapons?
Besides that, if you watched that other video I posted, just the NOISE and IMPACT FORCE's enough to make a important tactical advantage, you fail to understand the importance of harassment tactics in warfare it seems. Most battles in history were won by demoralizing the enemy, not number of casualties. (I'm talking about melee warfare, not modern day shooting)