The reasoning path to reach this suggestion is long and winded so, taking into account the general level of this forum population, I think it’s safe to leave it as an exercise for the reader.
The idea is to separate behaviour of shield and armor.
Reflects attacks below a minimum threshold
Regenerates until destroyed.
Reduces incoming damage by an amount equal to [resistance-armor penetration] (or some more elaborated equation if direct relation has any fault).
Hp, don’t self-heal.
Every time it’s hit, resistante is degraded.
Resistance doesn’t self-heal.
This allows for:
Armor with large resistance still playable.
Armor with large hp and no res is still different to large res and small hp.
HP Regeneratin armor can be a new module.
Res regenerating armor can be a new module.
Res regeneration modules can now exist.
Res bypassing weapons can now exist.
Res depleting weapons can now exist.
And thus, tanks can be built, but never lock the game with an unwinnable combination. (having changed linear opposition to rock paper scisors)
A tank could have huge resistance and res regenerators, but weak weapons that bypass it would triturate the low hp.
Another tank could have huge hp and hp regeneration, but high damage with res weakness weapons, would eventually break the res and overpower the hp regenerators.