Well, I was thinking about this for awhile... other then manually figuring out 20% over equipping rules for everything you plan on wearing, why not have the item itself con a certain color to let you know how much you can over equip it?
It's simple. You could give weapons a Con based on the % of reqs they have. It could work from Grey to lets say Blue (blue meaning cannot be overequipped without penalty).
The colors in the cons work the same as they do for mobs. Green is much lower what you could normally equip (based on your skills of course, anything below 20%, although wont effect it's useage will go grey to you, kind of like letting you know to upgrade that weapon). Yellow is the same as the reqs you currently have.
The most important part is the deep deep red (just before it Cons blue). Anything RED or below can be overequipped within the 20% based on your current skills. This way you could always know what weapons you can use and what weapons you cant.
The problem here is... well, what about buffs? I'm not sure how you equate self buffs into this conning system. Should the con of the weapon be based on the buffs you currently have in your NCU, or should they be based on base skill and implants alone. I'm not sure.
What is your opinion?