You know the feeling - your sovereign Lord Uberkiller, supreme master of Carnage, with his +50 Sword of Slaying anything (giving him a total Attack of 90) encounters a dying Wolf (1 Attack, 2HP), swings his mighty blade and... does 1 damage, the wolf retaliates for 1 damage. WTF?
While these kind of outcomes should be possible, they should be extremely unlikely, and not happen with 1:90 probability as it is right now. Similarly your Sovereign's Armor of utter Invulnerability (90 Defense) should not just roll a 0 against the Wolf's bite with a 1:90 chance.
Thus my suggesting:
In tactical combat each point of attack represents a 30% (20%? 40%? 50%?) chance to inflict 1 point of damage to the opponent - it will be unlikely that you do maximum damage, but neither will it be to do none. The same goes for defense - each point of defense has the same percentage chance to block 1 point of damage - again, you will have a nice average value with the extremes being unlikely.
As an example:
Lord-in-training Uberkiller, promising apprentice of Hurting-Things, has a attack of 3 (wooden sword) and defense of 2 (padded loincloth - don't ask). His opponent, the fearsome Target Dummy, has a attack of 1 (sharp splinters) and a defense of 1 (straw).
Lord-in-training Uberkiller strikes - the mighty Deity RNG rolls for his 3 points of attack (1-10, 3 or lower is a hit): 3, 1, 10 - Uberkiller slashes the dummy for 2 damage. Will the Straw protect the dummy? - Deity RNG rolls for the dummy's 1 defense (1-10, 3 or lower is a hit): 2 - Oh no! 1 of the 2 points of damage were prevented by the nefarious dummy's straw amor. And now the dummy threatens to harm Uberkiller with its sharp splinters; will Uberkiller win this fight? Will he even survive? Who knows, but sadly we must leave the scene of carnage...