They actually have the worst armor class. In Wizardry, 10 is considered to be your base AC and it goes lower as you equip more stuff (i.e. a low number or even a negative number means you're much harder to hit). So their AC of 8 would be just barely better than wearing a robe.
Right. Wizardry used the AD&D 1e and 2e method of determining accuracy, or something close to it. Aside from AC (Armor Class), the other stat determining whether an attack will hit is THAC0 (To Hit AC 0). The attacker will want to lower theirs, since the check is a d20 roll against (Attacker's THAC0 - Target's AC). So if Sakuya's THAC0 is 10, then they would need 10 or greater to hit someone with an AC of 0, and pretty much the only way that the attack won't hit Marisa or Alice is on a critical miss. (10-8 = 2 minimum to hit.) 3e and later would use Base Attack Bonus in place of THAC0, and change the formula for whether an attack hits to 1d20+BAB vs. AC, making higher numbers better for attack/defense.
