Cost : 6
Non-mounted units with a shield gain a aura with range 1 that gives every allied unit in range a 10% chance to evade a melee or ranged attack
Researched at barracks
10% is not high as a singular value. Infantry units are the most likely to die so it is more a matter of statistics.
The real strenght is in numbers
If you have a group of infantry units stuck together they all give a cumulative 10% to evasion.
A single unit might have 4 around it so it is a maximum of 40% evasion plus an extra 10% from shield block which is a whole 50% (until the formation is kept together).
In melee you can have 3 around (other than the side you are attacked) so you have a maximum 40%
This way you will greatly need to improve strategy. You'll need to carefully choose the ground to obtain the most from your shields.
This is also a great tactic to protect fragile units (eg spellcasters) that might have a 40% chance to evade arrows directed to them.
Dwarves will have higher base armor and might get similar techs with higher bonus
Humans are jack of all trades and they are well versed in every side of battle (but they should not excel in anyone even though they are the best in both naval battles and siege)
I try reducing dodge to special cases to keep simplicity. (And also because it is a random thing that is not good you can not count on many things, i mean less strategic)
But apart from these a well worn shield gives protection so armor is better to increase - imho.
I see, because in this case was a special ability. Also there are already things like catapults that have a failure chance.
This is meant to simulate the statistical chance of being hit in a battle by a flying arrow or a random hit.
Alo the effect of straing +1 armor in some cases is too much while a hit % is the same against all units (for example a +1 armor is negligible against a giant but a 10% miss chance works well even against a giant)
That would be one of those specific cases when % comes into play.