I proposed a fix for this in April. So, I'll repost a modified fix following closer to the description of the trait
https://dl.dropboxusercontent.com/u/75549875/Fallen%20Enchantress/Abilities/breakfix.zip
it simply adds the game modifier to the attack. (notice that it is a normal attack, unlike my previous fix, which accounted for all bonuses with the weapon)
<GameModifier>
<ModType>Unit</ModType>
<Attribute>DefendableDamage</Attribute>
<AttackStat>UnitStat_Attack_Pierce</AttackStat>
<Calculate InternalName="Value" ValueOwner="CastingUnit">
<Expression><![CDATA[[UnitStat_CominedAttack]]]></Expression>
</Calculate>
</GameModifier>
In my game however the defense bonus is removed, and oddity that may occur is that if the unit is defending and you add break it loses all defense, but if the unit is not defending and then defends it adds that extra defense giving them an effective 5 armor.