In CoreResources.xml there are a couple of lines that are repeated (the HideInHiergamenon element).

Lines 584/587

<ResourceType InternalName="ProtectFromSpellsType01">
        <DisplayName>Protect From Spells</DisplayName>
        <Type>ProtectFromSpells</Type>
        <HideInHiergamenon>1</HideInHiergamenon>
        <IconColor>0,0,0</IconColor>
        <Icon>Gfx//Icons//Electric_D_Stat_Icon.png</Icon>
        <HideInHiergamenon>1</HideInHiergamenon>
        <ModelColor>0,0,0</ModelColor>
        <Worth>1</Worth>
        <Global>0</Global>
        <Rarity>0.0</Rarity>
        <Shared>0</Shared>
        <TradedByCaravans>0</TradedByCaravans>
    </ResourceType>

and lines 707/711

<ResourceType InternalName="AirMagicType01">
        <DisplayName>Air Magic</DisplayName>
        <Type>AirMagic</Type>
        <Description>Air magic represents your power with air spells.</Description>
        <HideInHiergamenon>1</HideInHiergamenon>
        <IconColor>0,0,0</IconColor>
        <Icon>Gfx//Icons//Electric_Stat_Icon.png</Icon>
        <ClothIcon>gfx\\TacticalIcons\\MetalOre_1.png</ClothIcon>
        <HideInHiergamenon>1</HideInHiergamenon>
        <ModelColor>0,0,0</ModelColor>
        <Worth>5</Worth>
        <Global>1</Global>
        <Rarity>0.0</Rarity>
        <Shared>0</Shared>
        <TradedByCaravans>1</TradedByCaravans>
        <Medallions InternalName="Ration_Res_Medallions">
            <All>AirCrystal_Medallion.png</All>
        </Medallions>
    </ResourceType>