Arrows vs shields in dom2 and dom3

[mivayan]

I was curious about how shields protected from arrows in dom2 and dom3. Does the following match peoples' experience?

* arrows are better against shieldless units in dom3 than dom2
* but shields help a lot more.
* For a shield-less commander, a black steel tower shield is 7x better against arrows than an amulet of missile protection (but more encumbering).


A shortbow arrow hits a square in battle. One of the units in the square is always choosen as the target. The dom3 manuals definition of DRN (2d6, open ended) is same as in dom2.

Then comes a formula, which involves the shield. In dom2:
Attacker rolls: DRN
Defender rolls: DRN + shield defence

In dom3:
Attacker rolls DRN + (Size points in the square) +2 if magic weapon
Defender rolls 2 + DRN + (shield parry x2) - (Fatigue / 20)

Take a shortbow hitting a square filled with units (6 size points) which have no fatigue.

With no shield:
dom2- difference is +0, dom3 manual page5 table gives 46% chance to hit. Over half the arrows that hit a square with units miss in dom2? Seems low.
dom3- difference is +4, 76% chance to hit.

With a buckler which had def 1 in dom2, parry 2 in dom3
dom2: -1, 38%. dom2: +0, 46%

With round shield which had def 2 in dom2 and parry 4 in dom3. (vans, white centaurs)
dom2: -2, 30%, dom3: -4, 18%

With tower shield which had def 4 in dom2, parry 7 in dom3
dom2: -4, 18%, dom3: -10, 3% chance.

With a forged black steel tower shield which had def 4 in dom2, parry9 in dom3
dom2: -4, 18%. Dom3: -14, 1% chance.