I might be missing here, but it seems like you have just reworded what Aristox and I have already posted.
Perhaps I misunderstood what you and Aristox posted, but here is briefly how I got it:
Arixtox:
If a warrior wears 7 pieces of heavy metal armor and adds one more piece of light leather armor (not a +con, not a +dam, just some light protection), the total protection of the warrior becomes worse, not slightly better.
Q:
But that is completely counter-intuitive and contrary to common sense?
A:
Yes, but we don't care about common sense neither about looking for an alternative design to achieve the same goals while being more inline with human logic.
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Now, from my experience, such problems often result from skipping the steps in the common (software) development cycle. Just 'having requirements in my head' is not enough, once you write it down, you suddenly notice that certain parts are missing and some others contradict one another.
HLV, High Level Vision (goals) ->
Functional Spec (Rules and Constraints) ->
Requirements Spec (detailed check-list to be used against any suggested design) ->
Design (suggested Design and Architecture) ->
Technical Project (detailed description of the suggested implementation) ->
etc. etc.
If you jump directly from HLV to Design, chances are some of the requirements are neglected. In that case, it is important to come back and explicitely write down the list of requirements.
You are basically just rehashing things that have already been discussed and posted.
That's exactly what I do. Rehashing things in an orderly manner is often the difference between a successfull, well organized project and a chaotic, failed one.