There is a noticeable change when fighting blue vs yellow mobs. Yellow Mobs vs Blue Mobs:
Yellow mobs have higher stats
>>Yellow mobs have higher Weaponskill
>>>Yellow mobs have higher Defense Penetration

When Mob swings at shield user:
1. Check Position (Angle)
2. Check Evade 360 (Y/N)
3. Check Intercept (Y/N)
4. Check Guard (Y/N)
5. Check Number of Attacker Bonus (for Evade)
6. Check Dual Wield Bonus (Y/N for blocking)
7. Check 2-Handed Bonus (Y/N for parry)
8. Check Shield Type (for Blocking X # of Attackers/CAP)
9. Check GuardBot Shield Type
10. Check Evade (Y/N)
11. Check Parry (Y/N)
12. Check Block (Y/N)
13. Check GuardBot Block (Y/N)
14. Check Target Hit(Armor)
15. Check Miss (base,bonus,#ofAttackers,StyleBonus)
16. Check Damage (AF/ABS, swing speed etc...)
17. Check Proc Weapon (Y/N)
18. Check Damage Return (Y/N)
19. Check Proc Armor (Y/N)

The first check at which mob level has an impact is the check #15 After all defensive checks.
So if the yellow mob can't be defended against as well as a blue mob, it means that either the mob level has an impact on the defensive checks or that the check #15 is actually placed at a higher level in the checklist.

Let us consider when I am attacking a purple monster with a 1-handed weapon (parry). It is highly likely that he will parry, even more likely that I will miss. Usually, I will miss 80% of the time, and then it will parry some attacks. This must mean that the check# 15 is placed before the defensive checks. I think this is the core of the problem, the miss/hit has to be put after the defensive checks. When you swing, you swing at the sword=parry, the shield=block, the wind=evade, if the opponent fails to evade, to parry, to block, then you hit the enemy, where do you hit it? Torso 40% chance, did you just fail to crush the armor=miss check+bonus+etc..

Or there might be 2 Miss Checks:
- One miss check before all checks of 5%*(Level Difference) Miss (Y/N)
- one miss check before all checks of 1% Fumble (Y/N)
And then, once the weapon of the attacker reaches the armor of the defender, there is a Bust Armor Check (Chance to negate a blow).
If Armor is Busted, then there is the Damage Calculation.

At the moment the Hit/Miss check is one and only one, and it should be divided into base miss, base fumble, bust armor.
Bust armor should be placed after defensive checks.

Try 2 at the checklist:
When Mob swings at shield user:
1. Check Fumble (Y/N)
2. Check Miss (Y/N)
3. Check Position (Angle)
4. Check Evade 360 (Y/N)
5. Check Intercept (Y/N)
6. Check Guard (Y/N)
7. Check Number of Attacker Bonus (for Evade)
8. Check Dual Wield Bonus (Y/N for blocking)
9. Check 2-Handed Bonus (Y/N for parry)
10. Check Shield Type (for Blocking X # of Attackers/CAP)
11. Check GuardBot Shield Type
12. Check Evade (Y/N)
13. Check Parry (Y/N)
14. Check Block (Y/N)
15. Check GuardBot Block (Y/N)
16. Check Target Hit(Armor)
17. Check BUST (I Copyright This) Armor (base,bonus,#ofAttackers,StyleBonus)
17. Check Damage (AF/ABS, swing speed etc...)
18. Check Proc Weapon (Y/N)
19. Check Damage Return (Y/N)
20. Check Proc Armor (Y/N)

Is that checklist any good?
I would really like to know if the base chance to miss are independent of the chance to hit the armor.
Meaning that chance to miss/ fumble is tested before the weaponskill and armor bonus, etc.. is checked.
So two checks instead of one.

I would answer your question but have difficulties to understand what you want to know. Try to reformulate.

Weapon and armor bonus influences miss rate itself.

I play a paladin and I feel that the blocking is a little bit off, so I am trying to figure out the reason.
There must be a mistake in the defensive checklist.

Let us say my full armor is 25% bonus, while mobs do not have bonus%.
Let us say that each level difference increases chances to miss by 5% yellow mobs having a base chance to miss of 5%.
Let us say that the # of attacker to-hit bonus is 5% per attacker
Let us say that fumble rate is a flat 1%.
Let us say that I am level 40 with 40 in shield.
Let us say that I am wearing a large shield.
Let us say that i am fighting 3 blue mobs at the same time.
Let us say that my armor/shield condition are at 100%.
Let us say that mobs do not use any styled attack.
Let us say that I have 6 points into parry.
Let us say that the mobs are not dualwielding.
Let us say that the mobs do not have a 2-handed weapon.

1 of the mobs attack me:
-1% fumble =>99%
-5%*2=-10% miss =>89.1%
+5%*2=+10% #ofattackerbonus =>98.01%
-(5%+3%)=-8% parry =>90.1692%
-(5%+20%)=-25% block =>67.6269%
-25% armorbonus => 50.72%
So each mob has around 50% chance to hit me, while fighting three blue mobs.

Or is it:
-1% fumble
-10% miss
+10% #of attacker bonus
-8% parry
-25% block
-25% armor bonus
total= -59% chance to hit = 41% chance to hit

What I mean exactly I guess is how are the % chance calculated: independently or conditioned or a mix of both?
And what is the formula like?
It could be that fumble and miss are added together and then the result is then tested for evade/parry/block and the following result testes against armor/weapon bonus, style bonus.

This would mean following the same scenario:
-1% fumble
-10% miss
=89% hit
-8% parry
-25% block
=59.63% hit
+0% style
-25% bonus
=44.72%
+10% #of attacker
=49.19% to hit

Depending on the values the % chance can vary, I don't have any idea on the chance to miss per mob, the chance to fumble, the # of attacker bonus, the mob stats, etc...

It could be nice to have a clearer idea of the sequence of calculation.

Order of defense is not what you assume.

On Uthgard it is: evade => parry => block => fumble => miss.

Its a complex situation you face. A yellow mob will ofcourse be stronger in several regards than a blue. You will not be able to pinpoint that down to one fact as multiple stats change per level. There are a lot of numbers and formulas involved in melee. Even more in PvE. Also facing more than 1 mob adds another layer of complexity where your shield size starts to count and parry me be influenced.

Alright, thanks.
Next time I will try to have something a lot clearer, I will work on it.