MMH5.5 - Heroes of Might and Magic 5.5

Their bonus damage is ok. Actually, the Haven T6 were very, very overpowered in standard ToTe. Due to high speed and initiative, they just charge in round one and one-shot kill an enemy stack. The enemy does not have a chance to react.
On top of that, champions are also hard to kill. The same issue should be relevant for WGE; how did you adjust it there?

In WGE, Charge is one of the strongest abilities. It gives a +100% bonus for each tile traveled; however, the base damage of the Knights is reduced by a factor of 3-4. This means that they hit very weakly from a standstill (including dealing weak counter-damage), but the charge is very powerful. The application of the ability is limited by 2 things:
1) speed - in WGE, only flying units can have a base speed higher than 6; accordingly, all Knights have a base speed of no more than 6
2) heavy class (Armored) - many creatures have an ability based on the "shield wall": they only receive 50% damage if the opponent has moved 1 or more tiles to attack
Accordingly, Knights can be countered in 4 ways:
1) carefully avoid being charged or move out of the charge range
2) cover yourself with heavy class troops (they suffer less from the charge)
3) go on the defensive (defense reduces damage many times over)
4) quickly reduce the distance, not giving the Knights enough space to charge, including surrounding them
The general idea is this: a strong ability creates interesting tactics and countermeasures. If there is no strong ability, it does nothing; it's just cannon fodder. Therefore, in WGE, I strive to reveal as many abilities as possible (very rare abilities are weakened, but among them is Torpor).
Plus, a strong Charge is historically justified, because it is known that Knights are good in open areas, but in a confined space, they are of little use, and their effectiveness drops many times over (therefore, under such conditions, Knights often dismount). A 100% charge very well demonstrates this feature of cavalry. About a 10% charge, I would say that it at least minimally demonstrates this feature (the difference between a hit from a standstill and a full charge is 1.8 times). With 5% and even more so 3%, a Knight hits almost as effectively from a standstill as from a charge, i.e., it clearly cannot be said that it suffers in any special way from a confined space.

The ability looks strong on paper, but actually, you can only get to 0.1 if you charge it from a 9-square distance.

Not only on paper - on average, this ability performs no worse than agility in the original game (since the enemy usually runs a few tiles), but in your game, agility is weakened by a factor of 3. If a unit is too strong (and it is strong), then you can weaken its defense and/or damage (to the level of the upgrade).

Hm.. I do not understand this; could you elaborate? Here is how I see it. The unit has 6 attack and 6 defense and 7 speed. If he goes 7 tiles, his defense jumps to 13. This means that the damage resistance bonus is 7*3.33% ~ 23%.

If you replace this ability with a simple passive bonus of +5 to defense (conditionally), nothing will change significantly (the difference will be +/- 1-2 defense). This is precisely an indicator that the ability does not play out (in terms of interest).

Those things are good qualities by themselves, so it is alright if the unique ability is a bit weaker.

A bit weaker - is that translated as 3 times? :)

In WGE, agility works 2 times stronger than in the original and 6 times stronger than in your game (although the speed is lower, so in reality, it is 4 times stronger). This means that when a unit runs far, it receives good protection; but if a unit runs a little or stands still, it dies very quickly from attacks. The difference is acutely felt, and this is what makes the ability interesting. Similarly, with cavalry charge, there are many nuances in the use and counteraction of this ability.

How much attention do you pay in MMH5.5 in battle to preventing Knights or Dancers from running an extra tile? If there is only a 3% bonus, then there are clearly more important concerns than limiting their charge. Strengthening abilities is increasing the number of nuances by which you can win in battle; I am not advocating for this (since your project does not specialize in tactics), but at the same time, I note that reducing tactical nuances by weakening already existing abilities is bad.

However, there are abilities that really should be weakened, such as Torpor. What is the difference? The fact that even a heavily cut Torpor is good (no worse than blindness and no worse than a one-sided attack, at least in PvP). And the fact that it is difficult to make Torpor play well or badly; it is a random ability with a poorly controlled chance, i.e., there is no tactical reason to make it too strong. Unlike those abilities, the effectiveness of which directly depends on the player's actions.