About the AC: in fact, I don't really see what this atribute represent actually, why a guy in BA would be harder to hit (not hurt) than a guy in leather jacket? Logically, if it's about dodging, it would even be the opposite. The "armor class" make me think about it would represent "fiability" of an armor, representing the number and vulnerability of weak spots, so the resistance against criticals. But well, creating a new atribute for armor is fine too ;p
And about avenger... Well I think I don't explain my point well, tough I agree his pure DPS is better, I still think that it's more effective to make a LSW build.