Armor Levels?????

I have been playing GW for well over 800 hours now and have 4 characters at lvl 20. For the last month I have been trying to figure out armor levels. If I have all 5 peices of gladiator armor for my warrior at 80 armor each, does that mean I have armor level 80 or does it mean I have armor level 400 (5x80)? I have heard many people say I have armor level 80 but it really doesn't make sense to work it that way. Also I have concluded that all 5 peices of ascalon armor give you -5 damage from each hit, so is plate mail armor(5x85) 5 armor better than asclon(5x80) or is it 25 armor better? Which is better -5 damage or 5, or 25 armor? Please help guys, Thank you.

GW calculates hit locations, you have 80 armour.
Knights/Ascalon is -2 damage, and is global, rendering more than 1 piece redundant.
The +5 armour would be better than the -2 against anything that does reasonable damage, but since the Knights effect is global, you should get just 1 piece, and have the effect everywhere, rendering such comparison meaningless. Also note that plate gives +5, but loses +10 physical, making the net result +5 elemental, -5 physical compares to gladiators or collectors armour. Knghts also suffers a -10 physical compared to the gladiators/collectors armours. This, plus the energy bonus from Gladiators, makes Gladiators armour the unquestionable winner.
The optimum configuration for general purposes is Knights boots, Gladiators Leggings and Chest, Gladiators Gauntlets (or Stonefist for Hammer warrior), weapon attribute helm.