i was browsing through the LUA files and found something I think might be particularly useful to know. here it is, exactly as it appears in the data files.  there appears to be 2 definitions, one of which is currently active (the one appearing first), and the second of which appears to be disabled (its commented out). draw your own conclusions.
 
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#****************************************************************************
#**
#**  File     :  /lua/common/ArmorTypes.lua
#**  Copyright © 2008 Gas Powered Games, Inc.  All rights reserved.
#****************************************************************************
#
# Armor Type Definitions
#
ArmorTypes = {
    Unarmored = {
        Normal = 1.0,
        Hero = 1.0,
        SpellFire = 1.0,
        Spell = 1.0,
        Light = 1.0,
        Arrow = 1.0,
        Artillery = 1.0,
    },
    Normal = {
        Normal = 1.0,
        Hero = 1.0,
        SpellFire = 1.0,
        Spell = 1.0,
        Light = 1.0,
        Arrow = 1.0,
        Artillery = 1.0,
    },
    Heavy = {
        Normal = 1.0,
        Hero = 1.0,
        SpellFire = 1.0,
        Spell = 1.0,
        Light = 1.0,
        Arrow = 1.0,
        Artillery = 1.0,
    },
    Structure = {
        Normal = 1.0,
        Hero = 1.0,
        SpellFire = 1.0,
        Spell = 1.0,
        Light = 1.0,
        Arrow = 1.0,
        Artillery = 2.0,
    },
    Demigod = {
        Normal = 1.0,
        Hero = 1.0,
        SpellFire = 1.0,
        Spell = 1.0,
        Light = 1.0,
        Arrow = 1.0,
        Artillery = 1.0,
    },
}
#ArmorTypes = {
#    Unarmored = {
#        Normal = 1.0,
#        Hero = 1.0,
#        SpellFire = 1.0,
#        Spell = 1.0,
#        Light = 1.0,
#        Arrow = 1.25,
#        Artillery = 1.0,
#    },
#    Normal = {
#        Normal = 1.25,
#        Hero = 1.0,
#        SpellFire = 1.0,
#        Spell = 1.0,
#        Light = 1.0,
#        Arrow = 1.0,
#        Artillery = 1.0,
#    },
#    Heavy = {
#        Normal = 1.0,
#        Hero = 1.0,
#        SpellFire = 1.0,
#        Spell = 1.0,
#        Light = 2.0,
#        Arrow = 0.5,
#        Artillery = 2.0,
#    },
#    Structure = {
#        Normal = 0.75,
#        Hero = 1.0,
#        SpellFire = 1.5,
#        Spell = 1.5,
#        Light = 1.0,
#        Arrow = 1.0,
#        Artillery = 2.0,
#    },
#    Demigod = {
#        Normal = 1.0,
#        Hero = 1.0,
#        SpellFire = 1.0,
#        Spell = 1.0,
#        Light = 1.0,
#        Arrow = 0.5,
#        Artillery = 1.0,
#    },
#}