Some problems with the combat code:

[Kayen]

Your 'agility' statistic and your 'defensive skill' which makes up a portion of your AC value is what contributes to your 'chance to avoid melee' in the source.

Accuracy from items and spell effects is accounted for as well.

When YOU are attacked it checks the difference in level between YOU and attacker at derives the base line chance that you will be hit.

Then it subtracts from that value YOUR ( AC component[agility factor, defensive skills], spell and item bonus AVOIDANCE)

Then it adds back to that value the ATTACKER accuracy modifiers. (Accuracy from items / spells, Chance to Hit spell effects).

The final chance to hit value is then rolled to determine initial hit vs miss.